3444A_233_A_Insp_Man_Alco_Engine_Model_251.pdf

TP: 3444A

(HM&E MANUAL)

TECHNICAL MANUALS

INSPECTION MANUAL FOR ALCO

ENGINES – MODEL 251

MULTIPLE CLASS CUTTERS

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NESU NEW ORLEANS (1) (51259)

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NESU SEATTLE (1) (51253)

RES TRA CEN (NCT) (1) (63100)

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USCGC BEAR (1) (11501)

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USCGC FORWARD (1) (11511)

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USCGC THETIS (1) (11510)

USCGC ACTIVE (1) (12104)

USCGC ALERT (1) (12116)

USCGC CONFIDENCE (1) (12105)

USCGC DAUNTLESS (1) (12110)

USCGC DEPENDABLE (1) (12112)

USCGC DILIGENCE (1) (12102)

USCGC RELIANCE (1) (12101)

USCGC RESOLUTE (1) (12106)

USCGC STEADFAST (1) (12109)

USCGC VALIANT (1) (12107)

USCGC VENTUROUS (1) (12111)

USCGC VIGILANT (1) (12103)

USCGC VIGOROUS (1) (12113)

USCGC POLAR STAR (1) (14501)

USCGC POLAR SEA (1) (14502)

USCG YARD (IND) (1) (31800)

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Individual Manual Application Sheet

Technical Publications Number

3444A

Section Applicability

SWBS Number 233 SWBS Element Title

PROPULSION INTERNAL COMBUSTION

ENGINES

Section Identifier A

Equipment Functional Description

INSPECTION MANUAL FOR ALCO

ENGINES - MODEL 251

CI Functional Description ESWBS Code Remarks

Planset Hulls

400-WAGB 10, 11

618-WMEC 615, 616, 617, 618, 619

627-WMEC 620, 621, 623, 624, 625, 626, 627, 629, 630

901-WMEC 901, 902, 903, 904

905-WMEC 905, 906, 907, 908, 909, 910, 911, 912, 913

Inspection Manual for ALCO Model 251 Diesel Engines and Generator Sets

MPR-1673

Revision 4

Prepared for the

ALCO Owner’s Group

By

MPR Associates, Inc.

320 King Street

Alexandria, VA 22314-3230 703-519-0200

This document was developed for and is the property of the ALCO Owner“s Group (AOG) and MPR Associates, Inc.

The contents of this document may not be copied, in whole or in part, without the written permission of the AOG Project Manager. This document is applicable to ALCO Model 251 diesel engines and generator sets and is intended to supplement technical documentation and guidance provided by the Fairbanks Morse Engine Division. The AOG is not liable for any misuse of this document. All data, information, procedures, techniques, and guidelines contained in this document are proprietary to the AOG and MPR.

Inspection Manual for ALCO Model 251 Diesel Engines and Generator Sets

MPR-1673

Revision 4

January 2002

Prepared by:

Lance C. Elwell

Reviewed by:

Mark O“Connell

Approved by:

Christian L. Haller

Prepared for

ALCO Owner“s Group:

Canadian Coast Guard Pacific Gas & Electric Consumers Energy Public Service Electric & Gas Entergy Operations Rochester Gas & Electric Fairbanks Morse Engine Division Royal Australian Navy

United States Coast Guard

MPR-1673

Revision 3 ii

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Use of This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Mechanical Inspection Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.1 Mechanical Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1-1

3.2 Engine Description, Orientation, and Inspection Sequence . . . . . . . . . 3.2-1

Engine Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2-1

Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2-1

Inspection Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2-1

3.3 Piston Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-1

Inspection Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-2

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-2

Piston Crown Via Borescope or With Cylinder Head Removed . . . . . 3.3-3

Piston Interior With Piston Installed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-3

Piston Removed From the Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-3

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-3

Carbon Build-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-3

Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-3

Scoring/Galling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-4

Ring Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-4

Wrist Pin and Bushing Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-4

3.4 Cylinder Liners and O-Rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-1

Inspection Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-2

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-2

Top Half of Cylinder Liner Via Remote Methods . . . . . . . . . . . . . . . . . 3.4-3

Table of Contents (cont.)

MPR-1673

Revision 3 iii

Top Half of Cylinder Liner With Head Removed . . . . . . . . . . . . . . . . . 3.4-3

Bottom Half of Cylinder Liner With Piston Installed . . . . . . . . . . . . . . 3.4-4

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-4

Scoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-4

Scuffing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-4

Flange Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-4

Cylinder Liner Flange to Cylinder Block Joint . . . . . . . . . . . . . . . . . . . . 3.4-5

Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-5

O-Ring Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-5

Inadequate Surface Finish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-6

Cylinder Liner to Cylinder Block Diametral Interference Fits . . . . . . . 3.4-6

3.5 Cylinder Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-1

Inspection Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-1

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-1

Valves and Flame Face Via Remote Methods . . . . . . . . . . . . . . . . . . . . 3.5-2

Head with Head Removed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-2

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-2

Head Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-2

Valve Recession . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-2

Nozzle Sleeve Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-2

Compression Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5-3

3.6 Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-1

Inspection Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-2

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-2

Main Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-3

MPR-1673

Revision 3 iv

Connecting Rod Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-3

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-3

Particle Embedment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-3

Fatigue Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-4

Overlay Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-4

Fretting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-4

Main Bearing Cap Serration Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-4

Cavitation Erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-4

3.7 Valve Train Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7-1

Inspection Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7-1

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7-1

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7-1

Equalizing Yoke and Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7-1

Equalizing Yoke-to-Valve Stem Contact . . . . . . . . . . . . . . . . . . . . . . . . 3.7-2

Pushrod Socket and Ball Stud . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7-2

3.8 Fuel Injection Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-1

Inspection Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-1

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-1

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-1

Peak Firing Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-1

Injection Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-2

Pop Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-2

Spray Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-2

Seat Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-2

Nozzle Tip Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8-2

MPR-1673

Revision 4 v

3.9 Fuel Injection Pump Support, Cam Lobes, and Valve Pushrod

Lifters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-1

Inspection Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-2

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-2

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-3

Cam Lobe Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-3

Roller Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-4

Valve Pushrod Lifter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-4

Fuel Pump Crosshead Lifter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-4

Pins and Bushings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-4

Spun Camshaft Bearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-5

Camshaft Bearing Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9-5

3.10 Cylinder Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10-1

Inspection Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10-1

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10-1

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10-2

Cam Bearing Block Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10-2

Interference Fits with Cylinder Liner . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10-2

Cylinder Liner Flange to Cylinder Block Joint . . . . . . . . . . . . . . . . . . . 3.10-2

Cavitation Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10-2

3.11 Turbocharger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11-1

Inspection Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11-1

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11-1

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11-1

MPR-1673

Revision 4 vi

Blade Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11-1

Deposit Buildup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11-1

Generator and Controls Inspection Guidelines . . . . . . . . . . . . . . . . . . . . . 4-1

Electrical Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

4.1 Generator Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-1

Electrical Components Design Description . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-1

Electrical Components Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . 4.1-1

Borescopic Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-1

Thermographic Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-1

Visual Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-2

Megger Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-2

Polarization Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-2

High Potential Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-3

Voltage Drop Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-3

Slip Ring and Brush Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-3

Electrical Components Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . 4.1-4

Loose Laminations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-5

Winding Short Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-5

Moisture Ingress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-5

Slip Ring Out-of-Round . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-5

Slip Ring Surface Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-5

Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-6

Mechanical Components Design Description . . . . . . . . . . . . . . . . . . . . . . . 4.1-6

Mechanical Components Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-6

Temperature Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-6

Lubricant Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-6

Roller Bearing Lubricant Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-6

MPR-1673

Revision 4 vii

Journal Bearing Lubricant Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-6

Visual Bearing Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-6

Roller Bearing Visual Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-6

Journal Bearing Visual Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-7

Mechanical Components Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . 4.1-7

Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-7

Roller Bearing Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-7

Journal Bearing Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-7

Lubricant Breakdown or Contamination . . . . . . . . . . . . . . . . . . . . . . . . 4.1-7

Roller Bearing Lubrication Breakdown . . . . . . . . . . . . . . . . . . . . . . . 4.1-7

Journal Bearing Lubrication Breakdown . . . . . . . . . . . . . . . . . . . . . . 4.1-7

Bearing Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-7

Roller Bearing Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-8

Journal Bearing Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-8

Inadequate Generator Shaft Bearing Insulation . . . . . . . . . . . . . . . . . . 4.1-8

4.2 Governor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2-1

Design Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2-1

Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2-1

Visual Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2-1

Surveillance Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2-1

Degradation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2-1

Improper Governor Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2-1

MOP Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2-1

Special Inspection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.1 Surface Replication Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1-1

Surface Replication Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1-1

Porosity Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1-2

MPR-1673

Revision 4 viii

Surface Finish Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1-3

5.2 Blue Check Contact Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2-1

Cylinder Liner Flange to Cylinder Block Counterbore . . . . . . . . . . . . . . . . 5.2-1

Cylinder Liner to Cylinder Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2-2

Bearing Shell Backing to Saddle or Cap . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2-2

Main Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2-2

Connecting Rod Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2-3

5.3 Thermographic Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3-1

Uses of Thermographic Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3-1

Benefits of Thermographic Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3-1

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

Configuration Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Site Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Idea/Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

Revision 3 ix

Tables

4.1-1 Practical Guidance for Slip Ring Roundness Criteria . . . . . . . . . . . . . . 4.1-4

4.1-2 Typical Manufacturer Recommended Brush Pressures . . . . . . . . . . . . . 4.1-4

Revision 4 x

Figures

3.2-1 Schematic of ALCO Model 251 Vee Engine . . . . . . . . . . . . . . . . . . . . . 3.2-2

3.2-2 Piston and Cylinder Liner Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . 3.2-3

3.2-3 Firing Diagram for Standard Rotation 8-Cylinder ALCO 251s . . . . . . 3.2-4

3.2-4 Firing Diagram for Standard Rotation 12-Cylinder ALCO 251s . . . . . 3.2-5

3.2-5 Firing Diagram for Standard Rotation 16-Cylinder ALCO 251s . . . . . 3.2-6

3.2-6 Firing Diagram for Standard Rotation 18-Cylinder ALCO 251s . . . . . 3.2-7

3.2-7 Firing Diagram for Reverse Rotation 8-Cylinder ALCO 251s . . . . . . . 3.2-8

3.2-8 Firing Diagram for Reverse Rotation 12-Cylinder ALCO 251s . . . . . . 3.2-9

3.2-9 Firing Diagram for Reverse Rotation 16-Cylinder ALCO 251s . . . . . 3.2-10

3.2-10 Firing Diagram for Reverse Rotation 18-Cylinder ALCO 251s . . . . . 3.2-11

3.3-1 ALCO 251 Piston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-5

3.3-2 ALCO 251 Piston Crowns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3-6

3.3-3 Piston and Cylinder Liner Thrust and Non-Thrust Sides . . . . . . . . . . . 3.3-7

3.4-1 ALCO 251 Cylinder Liner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4-7

3.4-2 Cylinder Liner Flange to Cylinder Block Joint . . . . . . . . . . . . . . . . . . . . 3.4-8

3.5-1 ALCO 251 Cylinder Head Flame Face (M-1 Head) . . . . . . . . . . . . . . . 3.5-4

3.6-1 Main and Thrust Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-6

3.6-2 Connecting Rod Bearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6-7

3.6-3 Main Bearing Cap Serration Wear Inspection Method . . . . . . . . . . . . 3.6-8

3.7-1 Valve Train Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7-3

3.10-1 ALCO 251 Vee Cylinder Block Fit Locations and Typical

Crack Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10-3

Revision 4 xi

Record of Revisions and List of Effective Pages

Manual Revision

Revision Date

Summary of Revision

4 January

Revised the following Pages:

3.2-3, 3.3-1, 3.3-2, 3.3-3, 3.3-4, 3.4-1, 3.9-1, 3.9-2, 3.9-3, 3.9-4, B-1, C-1

Added the following Page:

3.9-5

Added the following Images:

3.4-25, 3.6-14, 3.8-9, 3.9-3, 3.9-4, 3.9-19, 3.9-20, 3.9-21, 3.9-22

Record of Revisions and List of Effective Pages

MPR-1673

Revision 3 xii

Manual Revision

Revision Date

Summary of Revision

3 December

Converted Manual to Electronic Format

Revised the following Pages:

i, ii, iii, iv, v, vi, vii, viii, ix, x, xi, xii, xiii, xiv, xv, xvi, xvii 3.3-1, 3.3-2, 3.3-3, 3.3-4, 3.3-7 3.4-1, 3.4-2, 3.4-3, 3.4-4 3.6-1, 3.6-2, 3.6-3, 3.6-4, 3.6-5, 3.6-6, 3.6-7, 3.6-8, 3.6-9 3.9-1, 3.9-2, 3.9-3, 3.9-4 4.2-1 6-2 Added the following Page:

3.6-10, 3.9-5 Added the following Images:

3.3-17, 3.3-18. 3.3-19 3.4-24 3.6-12, 3.6-13 3.8-8 3.7-6 3.9-13, 3.9-14, 3.9-15, 3.9-16 3.10-5, 3.10-6, 3.10-7, 3.10-8, 3.10-9 Deleted the following pages:

xviii, xix, xx, xxi, xxii, xxiii, xxiv, xxv, xxvi, xxvii Deleted the following Image:

4.2-1

Manual Revision

Revision Date

Summary of Revision

MPR-1673

Revision 3 xiii

2 December

Revised the following Pages:

i, ii, iii, iv, v, vi, vii, viii, ix, x, xi, xii, xiii, xiv, xv, xvi, xvii, xviii, xix 1-1 2-1, 2-2 3-1 3.1-1 3.2-1, 3.2-3, 3.2-4, 3.2-5, 3.2-6 3.3-1, 3.3-2, 3.3-3, 3.3-4, 3.3-5, 3.3-6, 3.3-7 3.4-1, 3.4-2, 3.4-3, 3.4-4, 3.4-5, 3.4-6, 3.4-7 3.5-1, 3.5-2, 3.5-3 3.6-1, 3.6-2, 3.6-3, 3.6-4 3.9-1, 3.9-2 3.10-2 3.11-1 4-1 6-1 A-2, A-3, B-1, C-1 Added the following Pages:

xx, xxi, xxii, xxiii, xxiv, xxv 3.2-7, 3.2-8, 3.2-9, 3.2-10, 3.2-11 3.9-3 4-2 4.1-1, 4.1-2, 4.1-3, 4.1-4, 4.1-5, 4.1-6, 4.1-7, 4.1-8 4.2-1 5.3-1, 5.3-2 6-2 Added the following Images:

3.3-16 3.4-23 3.5-16, 3.5-17, 3.5-18, 3.5-19

Manual Revision

Revision Date

Summary of Revision

MPR-1673

Revision 3 xiv

1 December

Revised the following Pages:

i, ix through xvii 3.4-5, 3.4-6 5.1-1, 5.1-2, 5.1-3, 5.1-4 A-3 B-1 Revised the following Images:

3.3-1, 3.3-10 3.4-10, 3.4-11, 3.4-12, 3.4-16, 3.4-17, 3.4-18 3.5-4, 3.5-5 3.11-1 Added the following Page:

xix Added the following Images:

3.3-12, 3.3-13, 3.3-14, 3.3-15 3.4-22 3.5-8, 3.5-9, 3.5-10, 3.5-11, 3.5-12, 3.5-13, 3.5-14, 3.5-15 3.6-9, 3.6-10, 3.6-11 3.7-3, 3.7-4, 3.7-5 3.8-3, 3.8-4, 3.8-5 3.9-8, 3.9-9, 3.9-10, 3.9-11, 3.9-12 3.11-8, 3.11-9, 3.11-10, 3.11-11, 3.11-12, 3.11-13, 3.11-14 5.1-1

0 April 1997 Initial Issue

Revision 4 xv

The current manual revision is comprised of the individual page revisions as listed below.

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Front Matter i 3 ii 2 iii 2 iv 2 v 2 vi 2 vii 2 viii 2 ix 2 x 2 xi 2 xii 3 xiii 3 xiv 3 xv 3 xvi 3

Section 1 - Introduction

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Section 2 - Use of This Manual

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Section 3 - Mechanical Inspection Guidelines

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Section 3.1 - Mechanical Definitions

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Section 3.2 - Engine Description, Orientation, and Inspection Sequence

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Section 3.4 - Cylinder Liners and O-Rings

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Section 3.5 - Cylinder Heads

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Section 3.6 - Bearings

3.6-1 3

3.6-2 3

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Section 3.7 - Valve Train

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Section 3.8 - Fuel Injection Nozzles

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Section 3.9 - Fuel Injection Pump Support, Cam Lobes and Valve Pushrod Lifters

3.9-1 4

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Section 3.10 - Cylinder Block

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Section 3.11 - Turbocharger

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Section 4 - Generator and Controls Inspection Guidelines

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4-2 2

Section 4.1 - Generator

4.1-1 2

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Section 4.2 - Governor

4.2-1 3

Section 5 - Special Inspection Techniques

5-1 0

Section 5.1 - Surface Replication Measurements

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Section 5.2 - Blue Check Contact Measurements

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Section 6 - References

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Appendix A - Configuration Summary

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Appendix B - Site Contact Information

B-1 4

Appendix C - Idea/Comments

C-1 4

Revision 2 1-1

Introduction

The purpose of this manual is to provide guidance for the evaluation of degradation of major engine and generator components in ALCO model 251 diesel engines and generator sets in nuclear and standby service and marine applications. This manual was prepared by the ALCO Owner’s Group (AOG) as a method to improve diesel engine and generator set reliability and availability through the identification and evaluation of component degradation. The intent is to provide general guidelines for diesel engineers and mechanics to identify the various modes of component degradation which may be unique to the operation of ALCO model 251 diesel engines and generator sets.

Due to the comparatively small number of operating hours per engine for nuclear standby applications, it has been difficult for any one electric utility or operator to develop expertise for a wide variety of degradation mechanisms. Thus, the information in this manual has been gathered from several nuclear utilities, and government sources, within the AOG as well as commercial sources and reflects a wide range of operating experience.

Section 2 describes the format and approach of the manual with specific instructions on how to use the manual. Sections 3 and 4 provide specific inspection guidelines for mechanical and electrical components, respectively. These sections make extensive use of photographs of degraded or failed components along with descriptions of the characteristics of the degradation, suggestions as to probable cause of the degradation, and recommendations regarding continued use of the parts or corrective actions. Section 5 provides instructions for special inspection techniques. Section 6 provides the references for technical information used in the manual, and the Appendices provide useful information to help the AOG members share site experiences and to provide input for future manual revisions.

It is the intent of the AOG that this manual be periodically revised to include the results of member experience and/or an increase in scope to include additional components.

While this manual is intended to serve as an inspection tool, the ALCO Technical Manual and Fairbanks Morse/ALCO (FM/ALCO) technical representatives and engineers should be considered the final references regarding continued operation of an ALCO 251 diesel engine.

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Use of This Manual

The purpose of this manual is to provide maintenance and operating personnel with a reference source which may be used to assist in evaluating the material condition of ALCO 251 diesel engine and generator set components. In this regard, Sections 3 and 4 provide inspection guidance for mechanical and electrical components, respectively. As a function of component, Sections 3 and 4 each provide a description of the component’s design, instructions for consistent identification, discussion of relevant inspection techniques, a summary of potential degradation modes, and inspection forms to record observations. Each section also includes photographs of actual components which exhibit various stages and modes of degradation. The photographs are provided with descriptions of the degradation characteristics, suggestions as to probable causes, and a recommendation regarding continued use of the part or corrective actions.

Section 5 provides instruction on specialized inspection techniques which are common to multiple components and/or would unnecessarily complicate the component discussions provided in Sections 3 and 4.

Section 6 provides references for technical information that are used within the manual.

The Appendices are designed to help the AOG share specific common experiences.

This section provides a configuration summary for many of the AOG ALCO 251 EDGs. The configuration summary identifies the product variations, site alterations, commonalities, and differences of the AOG ALCO 251 installations.

Also provided in this section is a site contact information list which provides the names and phone numbers of the AOG Technical Committee members. Lastly, the Appendices include an idea/comment page for suggested improvements and/or additional topics for inclusion in the manual.

The user should recognize that visual inspection techniques may be used in many cases to justify maintenance actions or continued operation of diesel engines and generator sets. However, in some cases, additional analysis, measurements, or tests may be required to make an adequate assessment of the material condition of components. It is inevitable that modes of degradation will be identified which are not represented in this manual. Further, the lists of possible root causes of the degradation modes presented may not be complete. In all cases, the ALCO 251 Technical Manual and FM/ALCO technical representatives and engineers at Beloit, Revision 2 2-2

WI should be considered the final reference regarding the continued operation of an ALCO 251 diesel engine or generator set.

During routine maintenance and corrective repairs, it is strongly encouraged that AOG members photograph unusual wear patterns and/or degradation modes that are encountered and that degraded components be preserved. Copies of photographs or video inspections, actual failed components, and/or root cause evaluations, should be submitted to the AOG Project Manager using the form provided in Appendix C. This direct experience with AOG root cause investigations, along with FM/ALCO guidance and general industry experience, form the basis for the recommendations and possible root causes that are provided in this manual.

Note: The images in this manual were obtained during actual site operations using commercially available equipment and, in some cases, the images are not ideal.

Some variation between the material conditions observed during an engine inspection and the images provided in this section is to be expected. These images should be used for guidance only. Where a question exists concerning suitability of a part for continued use, contact FM/ALCO for assistance.

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Mechanical Inspection Guidelines

This section provides specific inspection guidelines for mechanical diesel engine components. Subsections devoted to each component provide discussion of the component’s basic design, function, and any unique design features. The subsections also provide guidance on the proper identification labeling and terminology, applicable inspection techniques, and the likely degradation modes to be encountered. Lastly, extensive use is made of photographs to assist the AOG members in their component evaluations. The photographs show various stages and modes of degradation and provide descriptions of the characteristics of the degradation, suggestions as to probable cause of the degradation, and recommendations regarding continued use of the parts or corrective actions.

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3.1 Mechanical Definitions

Inspection and documentation of component conditions requires a careful use of terminology. Consistent terminology use by the AOG will enhance the sharing of operating experience. In this regard, several of the most common terms are defined below.

BDC: Acronym for “Bottom Dead Center” which refers to the condition when a piston is at its lowest position in the cylinder. Cylinder volume is at a maximum when the piston is at BDC.

EB: Acronym for “Equipment Bulletin.” FM/ALCO periodically issues equipment bulletins which augment and/or clarify maintenance instructions.

Excessive Carbon: Carbon accumulation in the ring grooves sufficient to prevent the rings from receding into the ring grooves so they are flush with the piston surface.

FOD: Acronym for “foreign object damage.” Term is typically used to describe impact damage to the airfoils of the turbocharger blading.

Galling: Displacement of surface metal due to a lack of lubrication. Galling is characterized by a raised metal surface and a rough “torn” appearance.

Light Scratching: Surface scratches which can be seen but not felt with the bare hand.

MI: Acronym for “Maintenance Instruction.” FM/ALCO provides numbered maintenance instructions of a component specific nature in the diesel engine and/or generator set technical manual.

Polishing: Characterized by a somewhat reflective appearance of the material surface. In the case of pistons, it results from “incidental” contact of the high spots on the piston and liner as the parts wear in.

Scoring: Linear gouges in the metal surface with material displacement or removal.

Scoring is the result of foreign particles lodged between two lubricated surfaces.

Score marks can be felt with a bare hand.

Spalling: Separation of plating or hardened layer from the base metal in large pieces.

Scuffing: Scuffing is a form of cylinder liner degradation that often has a blotched or rough, irregular shaped appearance. The roughened surface is usually intermittent and often can be seen but not felt. If present, scuffing usually occurs at the top or compression end of the cylinder [Chapter 10, Reference 2].

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TDC: Acronym for “Top Dead Center” which refers to the condition when a piston is at its highest position in the cylinder. Cylinder volume is at a minimum when the piston is at TDC.

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3.2 Engine Description, Orientation, and Inspection Sequence

Engine Description

ALCO 251 diesel engines are four-stroke engines with an inline 6 cylinder configuration as well as vee 8, 12, 16, and 18 cylinder versions. The engines are turbocharged, use wetted cylinder liners and heads for cooling, and have a side-by-side connecting rod arrangement from a common crankshaft pin. Figure 3.2-1 is a cross-section of a vee design which shows the overall arrangement of the engine and the various gas and fluid passages.

Orientation

Figure 3.2-2 illustrates an overhead or plan view of a typical ALCO 251 vee engine which shows the ALCO naming and orientation conventions. As the figure shows, the turbocharger is located at the “free end” or front of the engine and the generator or reduction gear is located at the “drive end” (rear) of the engine. The terms “free end” and “drive end” are the most commonly used terms to refer to the front and rear of the engine, respectively. The left and right sides (banks) of the engine are defined from the vantage point of looking towards the free end from the drive end. The engine cylinders are designated by their bank and numbered position. Cylinder numbering begins with “1” at the free end and ends with “6” (6 or 12 cylinder), “4” (8 cylinder), “8” (16 cylinder), or “9” (18 cylinder) at the drive end. As an example, the third cylinder on the left bank from the free end is referred to as “3L.”

Inspection Sequence

Figures 3.2-3 through 3.2-6 illustrate the standard rotation (counter clockwise when viewed from the drive end) firing order for ALCO 251 V-8, V-12, V-16, and V-18 engines, respectively. These figures should be used to optimize the order of cylinder inspections. For example, on a 16-cylinder engine, the firing order can be used to determine which pistons are located at TDC at the same time. Figures 3.2-7 through 3.2-10 provide the same information for reverse rotation (clockwise) engines.

Figure 3.2-1. Schematic of ALCO Model 251 Vee Engine

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Figure 3.2-2. Piston and Cylinder Liner Nomenclature

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Figure 3.2-3. Firing Diagram for Standard Rotation 8-Cylinder ALCO 251s

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Firing 3.2-4. Firing Diagram for Standard Rotation 12-Cylinder ALCO 251s

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Figure 3.2-5. Firing Diagram for Standard Rotation 16-Cylinder ALCO 251s

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Figure 3.2-6. Firing Diagram for Standard Rotation 18-Cylinder ALCO 251s

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Figure 3.2-7. Firing Diagram for Reverse Rotation 8-Cylinder ALCO 251s

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Figure 3.2-8. Firing Diagram for Reverse Rotation 12-Cylinder ALCO 251s

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Figure 3.2-9. Firing Diagram for Reverse Rotation 16-Cylinder ALCO 251s

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Figure 3.2-10. Firing Diagram for Reverse Rotation 18-Cylinder ALCO 251s

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3.3 Piston Assembly

Design Description

Figure 3.3-1 shows a typical ALCO 251 piston. Two types of pistons are in common use in ALCO 251 engines: the flat top type and the ” mexican hatµ type as illustrated in Figure 3.3-2. A third OEM piston type, namely the ” superbowlµ piston, is also available and is shown in Figure 3.3-2. Mahle, a non-OEM supplier, also manufactures a barrel-faced skirt version of an ALCO piston and also produces a design with a removable crown which permits piston ring replacement without pulling the connecting rod assembly. In all cases, the piston assembly consists of a temperature resistant forged steel crown and a forged aluminum alloy body. The crown is shrink fitted and bolted to the piston body (OEM design). Piston assemblies have an internal pressure-fed oil cavity to provide cooling for the piston crown and share the same body design. The crown has three ring grooves which hold compression rings and the skirt has two grooves for oil control rings (also known as oil scraper rings). For the flat top and mexican hat pistons, the upper oil ring is a conformable type (spring backed design) while the lower oil ring is a nonconformable type (does not use a spring). For the superbowl pistons, both oil rings are nonconformable types when used with open grain chrome cylinder liners.

The superbowl piston is similar to the mexican hat piston except that it has a higher compression ratio, deeper bowl, and visible valve reliefs. The superbowl piston is a ” pop up design,µ that is, it protrudes above the top of the cylinder liner up into the squeeze volume of the cylinder head.

Collectively, the set of rings is referred to as a ring pack and its design and materials are chosen to match the cylinder liner running surface.

The wrist pin is a floating type design. The pin has a floating fit in the piston and a running fit with the connecting rod bushing. The wrist pin assembly consists of the wrist pin and a sleeve which serves to seal the internal oil passages in the pin. The sleeve is fitted in the bore of the wrist pin and held in place by rolling each end which creates a tight friction fit. The inner diameter of the wrist pin has a small locking groove at each end. The sleeve is rolled into the groove to lock it in place and prevent lateral movement. The connecting rod bushing is press fit to the connecting rod and has a steel-backed bronze-lined split design. Finally, two snap rings mate with internal groves in the piston to hold the piston pin in place.

Original (vintage) piston bodies have five (5) holes in the upper oil ring groove on one side of the piston and the other side has three (3) holes. Proper piston installation results in the five hole side pointing towards the outside of the engine vee. As the oil coats the cylinder liner wall, the lube oil tends to flow and roll towards the outboard wall of the cylinder liner. This action floods the oil control ring groove as the oil is scraped from the cylinder liner wall. The two additional

Revision 4 3.3-2 holes provide extra capacity to help drain the oil. On the inboard side of the vee, the three holes help to prevent excess oil from accumulating in the ring groove from the oil drain. Installation of the piston rotated 180$ to that described (i.e, five hole side pointing towards the inside of the engine vee) will not produce any detrimental effects but may possibly increase oil consumption, especially for variable speed diesel engines [Reference 7].

Inspection Labeling

Pistons are identified by their cylinder number (e.g, ” 3Lµ ). Additionally, the orientation of the piston and the cylinder liner is important to the correct diagnosis of piston and cylinder liner degradation. This is because some forms of degradation are characterized, in part, by their location in the engine. In particular, the non-thrust side and thrust side of the piston and cylinder liner must be clearly identified.

The thrust side of the piston is defined as the side of the piston in contact with the cylinder liner during the power stroke. Figure 3.3-3 illustrates a simple piston, rod, and crankshaft assembly which can be used to determine the thrust side of a piston.

For a vee engine such as the ALCO 251, the thrust side of the piston is ” towardsµ the engine centerline for one bank (the left bank) and ” awayµ from the engine centerline for the other (right) bank. Note that this is based on a point of observation looking at the generator end of a counterclockwise rotating engine.

Experience indicates that labeling the piston with ” clockµ positions is a useful method to identify different parts of the piston; 12 o“clock is located towards the engine centerline. Figure 3.2-2 also illustrates this convention. Standard rotation ALCO 251 engines rotate counterclockwise when viewed from the drive end of the engine. Therefore, the 12 o“clock position will always be the thrust side of the pistons located on the left bank and the 6 o“clock position will be the thrust side for pistons located on the right bank. (Note: Non-standard rotation ALCO 251s rotate in a clockwise direction. On these engines, the location of the thrust sides of the pistons would be the opposite of that discussed above.) We recommend that the orientation of pistons and cylinder liners be identified as soon as they are removed from the engine. This will reduce the potential for confusion when trying to diagnose problems later. The cylinder number and bank, as well as the 3, 6, 9 and 12 o“clock positions should be identified on the pistons and cylinder liners using an indelible marker. In the event that multiple engines are simultaneously disassembled, the engine identity should also be included to prevent inadvertent mixing of engine components.

Inspection Techniques

Visu…