Att_19_161130_-_ECH_Helmet_Bracket_MFR_Redacted.pdf

UNITED STATES MARINE CORPS

MARINE CORPS SYSTEMS COMMAND

2200 LESTER STREET

QUANTICO, VIRGINIA 22134-5010

IN REPLY REFER TO

PMM113.2/668

6 December 2016

MEMORANDUM FOR THE RECORD

Subj: DIFFERENCES BETWEEN CURVED ENHANCED COMBAT HELMET BRACKET

ASSEMBLY DRAWING AND COMPUTER-AIDED DESIGN MODEL

Ref: (a) Computer-Aided Design (CAD) model, .stp file 136-00-

0001, dated 30 Sep 16

Encl: (1) Curved ECH Helmet Bracket Assembly, DWG NO. 136-00-

0001, Tobyhanna Army Depot, revision dated 9 Mar 10

1. Engineers at Natick Soldier Research, Development and

Engineering Center (NSRDEC) and Aberdeen Test Center (ATC) compared measurements in the Enclosure (1) drawing to the reference (a) model of the Enhanced Combat Helmet (ECH) Bracket

Assembly and found several discrepancies.

2. Product Manager, Infantry Combat Equipment provides the following clarifications for future manufacturing and procurement of the curved Enhanced Combat Helmet (ECH) bracket assembly:

a. Enclosure (1) drawing, Sheet 2, Section A-A: The dimensions in the model, reference (a), locating the center of the large curve (noted as “outline for elliptical outer surface” and shown as 3.50 inches and 2.00 inches on the drawing) and the radius (shown as 3.48 inches on the drawing) shall take precedence over the dimensions shown on the drawing.

b. Enclosure (1) drawing, Sheet 2, Zone C3: The dimension shown on drawing (0.250 ± 0.002 inch) for the slot width shall take precedence over the dimension for the same feature in the model (0.255), reference (a).

c. Enclosure (1) drawing, Sheet 2, Zone C-5/6: The dimensions in the model, reference (a), for the radius of the left and right edges of the bracket (1.378 and 1.390 inches respectively) shall take precedence over the dimensions shown on the drawing (shown as 1.375 inches).

Subj: DIFFERENCES BETWEEN CURVED ENHANCED COMBAT HELMET BRACKET

ASSEMBLY DRAWING AND COMPUTER-AIDED DESIGN MODEL

d. Enclosure (1) drawing, Sheet 3, Detail F: The dimensions in the model, reference (a), for radius of the back edge of the section (3.364 inches) shall take precedence over the dimensions shown on the drawing (shown as 3.370 inches).

e. Enclosure (1) drawing, Sheet 3, Detail C: The drawing does not show a 0.050 x 45° chamfer (see pictorial views below) whereas the model has the feature. The model, reference (a), shall take precedence over the drawing.

3. Point of contact is Major John Draper, Project Officer for

Enhanced Combat Helmet, at 703-432-3656 or john.draper@usmc.mil.

C. A. BELL

Product Manager

Infantry Combat Equipment

Drawing Model