DEA Helmet Protocol 2019.pdf

DEA AND FBI BALLISTIC RESEARCH FACILITY

BALLISTIC HELMET TESTING PROTOCOL

Scope: This document outlines the procedures and methods by which an independent laboratory will conduct performance testing of ballistic helmets for service with DEA and FBI.

16 sample helmets, all size large, must be submitted for testing:

8 Complete Helmets are required for Penetration/Backface Deformation Resistance

2 Complete Helmets are required for Non-ballistic Impact attenuation.

1 Complete Helmet is required for Compression resistance testing and will also be used for static chin strap/buckle strength testing

1 Complete Helmet is required for Dynamic Chin Strap Retention Strength.

2 Finished Shells are required for Fragmentation testing

2 Complete Helmets as reserve helmets

I. DEFINITIONS: The following definitions shall apply throughout this document:

Ambient Temperature Condition: Complete helmet is conditioned for 24 hours (+/-2 hours) at 70˚F (+/- 10˚F).

Backface Deformation (BFD): Bulging/deformation on the interior of the helmet shell as a consequence of a test shot on the helmet.

Ballistic Clay: Roma Italian Plastilina No.1 modeling clay at ambient temperature.

Basic Plane: The plane passing through the ear openings and lower edges of the eye sockets.

Cold Temperature Condition: Complete helmet is conditioned for 24 hours (+/-2 hours) at -40˚F (+/- 10˚F). Once conditioned, and after removing the helmets from the environmental chamber, there is no requirement to maintain the helmets at the cold temperature during testing.

Complete Helmet: A Complete Helmet shall consist of a Finished Shell, a suspension and retention system attached to the Finished Shell, and any accessory mounts attached to the Finished Shell. A Complete Helmet shall be an “as worn by the end user” condition.

Coronal Plane: The plane perpendicular to the Basic and Mid-sagittal planes and passing through the centers of the ear openings.

Fair Shot Velocity: A test projectile shot resulting in an approximate impact velocity of 1400 f/s (+50/-25 f/s).

Finished Shell: A Finished Shell shall include the ballistic shell material, edge banding (if applicable), with any designed attachment holes and any primer/paint/coating. The Finished Shell is not refined for use as a helmet by the end user.

Hardware Shot: A fair velocity shot impacting directly on a fastener.

Headform: The headforms used throughout testing are the 2nd generation peepsite headforms. There are 5 headforms (front, right, left, rear and crown) and a headform mold which is used to contour and press the ballistic clay in each headform. Headforms conform generally to a size large helmet.

Helmet Crown: The area of the helmet 50mm radius from the approximate intersection of the Coronal plane and mid-sagittal planes.

Hot Temperature Condition: Complete helmet is conditioned for 24 hours (+/-2 hours) at 140˚F (+/- 10˚F). Once conditioned, and after removing the helmets from the environmental chamber, there is no requirement to maintain the helmets at the hot temperature during testing.

Mid-sagittal plane: The plane perpendicular to the Basic and Coronal planes and bisecting the head front to rear.

Next to Hardware Shot: A fair shot impacting adjacent to a fastener. Shots will be directed to the portion of the fastener farthest from the finished edge of the helmet (closest to the crown). The primary strike point of these test shots is on the ballistic material next to a fastener. Ideally the shot will make minimal contact with the edge of the fastener also.

Reference Plane: The plane approximately 60mm above, and parallel to, the Basic Plane.

Test Projectile: 124gr 9mm (NATO) FMJ with enclosed base. This test projectile is available from Federal Cartridge Company, part number 706236. Nominal impact velocity of test shots shall be 1400 f/s (+50/-25 f/s). Test projectile will be fired from a barrel with a rate of twist of 1:10 (+/- .25”). Typically the test projectile is hand-loaded to achieve the required velocities.

Water Conditioned: Complete helmet is totally immersed in tap water for 8 hours (+/-2 hours). Water temperature shall be 70˚F (+/- 20˚F). Weights may be placed in the helmet to keep a positively buoyant helmet submerged. Once conditioned, and after removing the helmets from the water the helmets should be allowed to dry (crown up) for 24 hours before conducting penetration/BFD resistance. There is no requirement to maintain the helmets in a wet condition during testing.

II. TESTING PROCESS

A. INSPECTION: All samples will be inspected using the Inspection Checklist in Appendix A.

1. Materials: All helmet materials must be non-hydroscopic and corrosion resistant.

Hardware used in the construction of the Complete Helmet shall remain corrosion free for the service life of the helmet. The 2 helmets randomly selected to be water conditioned for the penetration resistance testing shall be weighed before and after water conditioning. Subsequent to water conditioning, the helmets will be allowed to drain, crown side up, for 24 hours (+/-2 hours). The helmets will then be weighted again to determine the after weight. The difference in helmet weights after water conditioning must be less than or equal to 0.125 pounds when compared to the initial weights. Helmet after weights must be taken prior to conducting penetration/BFD resistance testing.

2. Shell Finish: The outer surfaces shall be, in general, finished smooth and evenly.

A mild friction (rough) surface treatment evenly applied across the surface of the shell is acceptable. There shall be no exposed fabric/fiber ends showing. Both the inner and outer shell shall be free from any hole (except as required to accommodate suspension, retention, and accessory mounting), delamination, blistering, cracks, depressions, peeling, or similar defects that prevent the surface from being smooth and continuous. There shall be no raised fibers, pleats, folds, wrinkles or creases longer than 25mm. Patching/repairs of the ballistic material cannot be performed after the ballistic shell material is molded. No more than 1 finish flaw per helmet is acceptable.

3. Construction: If the finished shell is of multi-material construction (ex: carbon fiber outer shell and ballistic inner shell) no separation of ballistic material from outer shell shall exceed a 1.5mm gap x 30mm in length and shall not extend more than 10mm into shell when measured from the finished edge. No more than 1 such flaw per helmet is acceptable.

4. Coatings: A coating (paint) shall be applied uniformly to the outer surface of the finished shell extending to visible edging. Interior coating of the Finished Shell is not required. The coating shall be free of defects (wrinkles, blisters, delamination, cracks, peeling, etc).

5. Shell Shape: The shape of the finished helmet shall conform to the general shape of the human head, having continuous curvature with no sharp angles.

B. Weight: 5 complete, mid-cut, size large helmets will be randomly selected by the testers for weight evaluation. Each complete helmet will be weighed individually and weights recorded. Each helmet must weigh 4.00 pounds or less.

C. Penetration Resistance Testing:

1. A total of 8 randomly selected complete helmets will be tested for penetration resistance. 2 helmets will be tested in each of the following conditioned states:

Ambient temperature; Water conditioned; Cold temperature; Hot temperature (each defined above).

2. Prior to helmet conditioning, the intended location for each test shot will be marked on the outside surface of the shell. Refer to Appendix B for shot placement locations. A horizontal line shall be marked at the required obliquity and distance from the finished edge of the helmet. For a shot to be fair the test projectile must touch the marked horizontal line.

3. Each helmet shall be attached to a validated headform using only the helmet retention system to secure the helmet to the headform. The retaining system shall be made snug such that movement of the helmet on the headform is minimized.

4. The helmet fixture shall be positioned such that the impact surface of the test sample helmet is 5m (+/- .5m) from the muzzle of the test barrel. The helmet fixture shall be adjusted for each shot in accordance with the shot schedule found in Appendix B such that each shot impacts at approximately 90˚ (0˚ NATO) obliquity to the shell/hardware surface.

5. After each shot, the helmet will be examined for penetrations before removing the helmet from the headform. The helmet shall be removed from the headform, with testers being careful not to disrupt the impact site in the ballistic clay. Once removed from the headform, the helmet interior will be inspected for penetrations.

6. Following the helmet inspection, the headform will be inspected for perforations in the ballistic clay. No fragments shall be extracted from the ballistic clay until the depth of the BFD has been determined.

7. For any test shot on the ballistic shell or on the hardware, a perforation of the shell by the test projectile or fragment of the test projectile that enters the headform clay shall constitute a penetration of the helmet. Any offeror’s sample that suffers a penetration of the shell by the test projectile shall be eliminated from further testing.

8. Non-metallic material such as paint, edging, fibers, resin, fragments of padding, Velcro pad retainers, plastic from buckles or similar material dislodged from the retention system of the test sample into the ballistic clay shall not constitute a penetration.

9. For any next to hardware shot only, evidence of the test projectile, fragment of the test projectile, fastener or fragment of the fastener in the ballistic clay having an aggregate weight more than 5.0 grains constitutes a penetration and that offeror’s samples will not be tested further. Any fragment or combination of fragments weighing equal to or less than 5.0 grains shall constitute a partial penetration.

Non-metallic material is ignored. A sample suffering a partial penetration during a next to hardware shot only shall continue being evaluated.

10. An unfair shot velocity exceeding 1450 f/s will be shot again on a reserve helmet.

11. An unfair shot below 1375 f/s that results in a penetration shall constitute a helmet failure and will not be repeated. Additionally, that offeror’s samples will not be tested further. An unfair shot below 1375 f/s that does not result in a penetration shall be shot again on a reserve helmet.

12. Make-up shots cannot be conducted in a location closer than 90mm to any other shot on the reserve helmet. The shot location can have no evidence of damage from previous shots (delamination, folds, depressions). Make-up shots shall be as close to the specified original location as possible and must maintain the same distance from the finished edge (25mm, 60mm, 90mm) Make-up hardware and next to hardware shots should be conducted last to ensure the helmet’s retention system is as intact as possible for any other shots on the helmet.

D. Backface Deformation testing:

1. Concurrent with the penetration testing, BFD shall be measured after each shot that does not result in a penetration.

2. Prior to each shot the headform shall be prepared in accordance with Appendix C.

3. Following each penetration resistance shot, and subsequent to the removal of the helmet, the depth of any resulting BFD shall be measure to the nearest 0.1 mm (fractions rounded off) using a FARO arm. Any cratering effect on the clay surface around the impact location will be ignored and only the depth from the initial surface will constitute the BFD dimension.

4. BFD shall not exceed the following allowed dimensions by location: Front 20.0mm, Right, Left, Rear and Crown 15.0mm (refer to location description in the shot schedule located in Appendix B).

5. The offeror is allowed 1 BFD in excess of the allowed dimension, provided it does not exceed 30.0mm front/20.0mm any other location. Testing will continue as long as no more than 1 shot results in BFD over the allowed dimension. At the conclusion of the BFD shots the sample mean BFD of the other 43 shots (omitting the excessive shot) will be calculated, and the standard deviation determined.

a. If the BFD of the shot in excess of the allowed BFD is less than the mean BFD plus 3 standard deviations the helmet has failed BFD testing.

b. If the BFD of the shot in excess of the allowed BFD is greater than the mean BFD plus 3 standard deviations that shot will be repeated. The make-up shot will then be fired on a reserve helmet in the required location. If the make-up BFD is in excess of the allowed dimension (20mm/15mm), the helmet has failed the BFD testing. If the Make-up BFD is within the allowed dimension the helmet passes the BFD testing.

6. Any persistent deformity to the interior of the helmet shell that would prevent the helmet from being mounted on the headform for additional testing may be reduced, at the discretion of the tester. Care must be taken to ensure that pads, liner material and retention straps are not damaged or moved from areas of the helmet that have not yet been tested.

E. Fragmentation testing:

1. Ballistic Limit Protection testing, referred to as V50 BL(P) or simply V50, will be conducted on 2 helmets at ambient temperature.

2. The 17 grain fragment-simulating projectile (FSP) as described in MIL-DTL-

46593B shall be used for the V50 testing. A mounting fixture and setup similar to that described in TOP 10-2-217 Ballistic Testing of Helmets for frag V50 testing (3.3.5.2 describes the test fixture, 4.5 is general V50 test procedure, and

4.5.3 describes the up and down method) shall be used to conduct the testing. The helmet will be sectioned in a similar manner to that described in TOP.

3. Required minimum V50 velocity is 2050 ft/s.

4. The following process shall be used to determine the V50 BL (P):

a. The V50 for each helmet shell shall be the average of at least 10 fair impact velocities consisting of an equal number of the lowest complete penetration and the highest partial penetration velocities provided that the velocity spread is not greater than 150 f/s.

b. In cases where the velocity spread is greater than 150 f/s, the V50 shall be the average of at least 14 fair impact velocities consisting of an equal number of the lowest complete penetration and the highest partial penetration velocities with a velocity spread no greater than 175 f/s.

c. If neither the 10 nor the 14 shot conditions can be satisfied, and at least 7 partial penetrations at velocities in excess of 2050 f/s and there are no complete penetrations at or below 2050 f/s, and at least 14 fair shots have been made in the helmet(s) it shall be determined to have satisfied the threat condition requirement.

d. Should none of these three conditions apply the sample has failed the V50 testing. The offeror’s samples will not be tested further.

5. No more than 3 shots per section are allowed. There may be no delamination overlap between shots.

6. If more than the 2 designated helmets are required to generate sufficient shots for V50 determination, a reserve helmet may be used for the additional shots.

7. The range setup shall be similar to the penetration testing specifications, with velocities being taken at the center point of the screens rather than impact velocities.

F. Non-ballistic testing

1. Impact Testing: 2 helmets at ambient temperature shall be tested in accordance with DOT-218, with the following variances: impact velocity of 10 f/s (+/- 3%) is achieved, 1 drop on each location is conducted. All impacts shall be on a hemispherical anvil using a size large headform. Drop location shall be on or about the following locations: mid-sagittal plane on front; intersection of the reference plane and mid-sagittal plane on the rear; Coronal plane – both right and left sides with the anvil striking above any ear protrusions; mid-sagittal and coronal intersection (crown).

2. Compression Resistance:

a. The helmet shall be resistant to compression from top to bottom. A sample helmet shall be shimmed such that the coronal and mid-sagittal planes are both approximately perpendicular to a flat testing surface (ex:

helmet placed on floor, 3 x 150mmx150mmx19mm plywood blocks stacked under the brim). Shimming shall not restrict the flexing of the helmet. Shimming is intended only to maintain the orientation of the helmet for testing. The helmet should not be attached to any shim material. The shimming material should be reasonably rigid. Plywood blocks or similar material is acceptable.

b. A compressive force of 400 pounds shall be brought gently into contact with the helmet, but not applied to the helmet. The top to bottom dimension of the helmet shall be measured to the nearest mm. The load will then be applied to the crown of the helmet and maintained for 30 seconds. The helmet shall be subjected to the test force 5 times in succession. The force application cycle shall be approximately 30 second intervals (+/-5 seconds) between each application of the test force. At the end of the fifth compression the top to bottom dimension will again be measured while the load remains applied to the helmet. The helmet top to bottom deflection must be 15mm or less. Following compression testing there shall be no visible delamination, ply separations, distortions or similar damage to the helmet shell. If a helmet exceeds 15 mm deflection it has failed and will not be tested further.

c. The helmet shall be resistant to compression from side-to-side. The same sample helmet shall be shimmed such that the coronal plane is perpendicular with the test surface and the mid sagittal plane is parallel with the test surface. A compressive force of 300 pounds shall be brought gently into contact with the side of the helmet. The side-to-side dimension of the helmet shall be measured to the nearest mm. The load will then be applied to the side of the helmet for 30 seconds. The helmet shall be subjected to the test force five times in succession. The force application cycle shall be approximately 30 second intervals (+/-5 seconds) between each application of the test force. At the end of the fifth compression the side-to-side dimension will again be measured while the load remains applied to the helmet. The helmet side to side deflection must be 15mm or less. Following compression testing there shall be no visible delamination, ply separations, distortions or similar damage to the helmet shell. If a helmet exceeds 15 mm deflection it has failed and will not be tested further. Only one side-to-side compression test will be conducted, the side (right/left) onto which the load is applied is at the discretion of the tester.

d. The helmet shall be resistant to compression from front-to-back. The same sample helmet shall be shimmed such that the mid-sagittal plane is perpendicular to the testing surface and the coronal plane is parallel to it.

A compressive force of 300 pounds shall be brought gently into contact with the front/back of the helmet. The front-to-back dimension of the helmet shall be measured to the nearest mm. The load will then be applied to the front/back of the helmet for 30 seconds. The helmet shall be subjected to the test force five times in succession. The force application cycle shall be approximately 30 second intervals (+/-5 seconds between each application of the test force. At the end of the fifth compression the front-to-back dimension will again be measured while the load remains applied to the helmet. The helmet front-to-back deflection must be 15mm or less. Following compression testing there shall be no visible delamination, ply separations, distortions or similar damage to the helmet shell. If a helmet exceeds 15 mm deflection it has failed and will not be tested further.

3. Retention Buckle/Strap Strength: The helmet retention strap shall have adjustable straps to facilitate proper fitment. The chinstrap shall remain secure in the adjusted configuration. One compression test helmet will be tested for Static Strength testing, and one helmet will be used for Dynamic Strength testing.

a. Static Strength: Adjust the retention system to the ballistic headform dimensions. The helmet then shall be securely held in a fixture similar to DOT FMVSS section 571.218, figure 4 (retention system test device).

The webbing shall be marked in a suitable manner such that slippage at the adjustment points may be verified. A load of 150 pounds shall be applied to the fastened chinstrap at a rate of 1.0 (+/-.10) inch/minute. The load shall be maintained for one minute (+/-5 seconds). No component of the retention system shall fail, the chinstrap buckle shall not open, and none of the adjustments shall slip. The webbing is allowed to stretch, but fasteners are not allowed to slip.

b. Dynamic Strength: One helmet at ambient temperature shall be tested in accordance with DOT-218, with the variance that an impact velocity of 25 f/s (+/- 3%) is achieved. All impacts shall be on a hemispherical anvil using a size large headform. Drop location shall be on or about the following locations: Reference plane and mid-sagittal plane at both the front and rear; Reference plane and Coronal plane – both right and left sides with the anvil striking above any ear protrusions; mid-sagittal and coronal intersection (crown). No component of the retention system shall fail. The chinstrap/buckle shall not release. Straps shall not slip.

APPENDIX A

INSPECTION CHECKLIST

DEFECT PASS FAIL COMMENTS

Materials Corrosion resistant Non-hydroscopic Before wt: After wt:

Shell Finish

Bubbles Cracking Depressions Exposed fibers Folds Peeling Pleats Sharp edges Wrinkles

Construction Material separation

Edging

Folds Gaps Peeling Pleats Separation Sharp edges Wrinkles

Coatings

Blisters Bubbles Cracking Delamination Peeling Wrinkles

APPENDIX B

SHOT SCHEDULE

SHOT

ORDER

TEMP

CONDITION

HEAD

FORM

HELMET

SAMPLE

SHOT

ID LOCATION DESCRIPTION

AMBIENT

FRONT

1-1 Front, along the mid-sagittal plane, 25mm from edge

2 RIGHT 1-2 Right, along the coronal plane, 60mm from edge

3 CROWN 1-3 Crown, right front 45˚

4 LEFT 1-4 Left, along the coronal plane, 60mm from edge

5 REAR 1-5 Rear, along the mid-sagittal plane, 90mm from edge

6 RIGHT 1-6 Rear, next to right suspension bolt*

7 FRONT

2-1 Front, left 315˚, 25mm from edge

8 RIGHT 2-2 Front, right 45˚, 90mm from edge

9 CROWN 2-3 Crown, left 270˚

10 LEFT 2-4 Rear, left 225˚, 60mm from edge

11 REAR 2-5 Rear, on right rear suspension bolt*

WATER

CONDITIONED

FRONT

3-1 Front, along the mid-sagittal plane, 60mm from edge

13 RIGHT 3-2 Right, along the coronal plane, 25mm from edge

14 REAR 3-3

Rear, along the mid-sagittal plane, 60mm from edge

15 CROWN 3-4 Crown, Right Rear 135˚

16 LEFT 3-5 Left, along the coronal plane, 90mm from edge

17 REAR 3-6 Rear, next to left rear suspension bolt*

18 FRONT

4-1 Front, left 315˚, 60mm from edge

19 RIGHT 4-2 Front, right 45˚, 25mm from edge

20 REAR 4-3 Rear, right 135˚, 90mm from edge

21 CROWN 4-4 Crown, Front 0˚

22 LEFT 4-5 Rear, on left rear suspension bolt*

SHOT

ORDER

TEMP

CONDITION

HEAD

FORM

HELMET

SAMPLE

SHOT

ID

LOCATION DESCRIPTION

HOT

LEFT

5-1 Left, along the coronal plane, 60mm from edge

24 REAR 5-2 Rear, along the mid-sagittal plane, 25mm from edge

25 RIGHT 5-3 Right, along the coronal plane, 60mm from edge

26 CROWN 5-4 Crown, Rear 225˚

27 FRONT 5-5

Front, along the mid-sagittal plane, 90mm from edge**

28 LEFT 5-6 Front, next to left front suspension bolt*

29 REAR

6-1 Rear, left 225˚, 90mm from edge

30 RIGHT 6-2 Rear, right 135˚, 25mm from edge

31 FRONT 6-3 Front, right 45˚, 60mm from edge

32 CROWN 6-4 Crown, 90˚

33 FRONT 6-5 Front, on left front suspension bolt*

COLD

FRONT

7-1 Front, along the mid-sagittal plane, 60mm from edge

35 LEFT 7-2 Left, along the coronal plane, 25mm from edge

36 REAR 7-3 Rear, along the mid-sagittal plane, 60mm from edge

37 CROWN 7-4 Crown, front 315˚

38 RIGHT 7-5 Right, along the coronal plane, 90mm from edge

39 FRONT 7-6 Front, next to right front suspension bolt*

40 LEFT

8-1 Front, left 315˚, 90mm from edge

41 REAR 8-2 Rear, Left 225˚, 25mm from edge

42 RIGHT 8-3 Rear, Right 135˚, 60mm from edge

43 CROWN 8-4 Crown, rear 180˚

44 FRONT 8-5 Front, on right front suspension bolt*

*For helmets without hardware visible on the exterior of the ballistic shell, the hardware/next to hardware shot will be made over the retention mounting location.

**If the helmet has an NVG mount, this shot will be on the mounting hardware nearest to the designated shot location

APPENDIX C

HEADFORM PREPARATION FOR TESTING

Peepsite Generation 2 headforms shall be used for penetration and BFD resistance testing.

The following sequence will be followed preparing headforms for each shot:

The headform shall be packed with ambient temperature Roma Italian Plastilina No.1 modeling clay. The clay must be packed such that no voids are present in the clay.

The headform is then pressed in the mold. Any excess clay shall be removed and the surface of the molded clay smoothed inspected for deformities.

The headform is then scanned using a FARO arm and Geomagic software (or similar).

The headform will then be validated at the approximate location of the intended shot.

Validation shall be conducted at ambient temperature. For validation, a spherical steel mass, 63.5mm diameter and 1.045kg, shall be dropped from a height of 2.0 m onto the headform at the approximate location behind the intended shot location marked on the helmet. The headform is then scanned again using the FARO arm and the resulting deformity depth recorded. To be valid for testing the depression must be 14mm (+/- 2mm fractions rounded off to nearest mm).

The headform is then remolded, the surface smoothed and inspected for deformities, and then scanned again by the FARO arm.

The validated headform is then placed in a fixture for testing. The sample helmet is mounted on the headform using the retention system of the helmet and the headform adjusted for the shot.

The sample helmet is then shot. Fair/unfair velocity for the shot is then determined.

Penetration is then determined.

The sample helmet is then carefully removed and the headform scanned by the FARO arm. The resulting BFD is then recorded.

SHOT LOCATION DIAGRAM KEY

Front of Helmets

X-1

X-2

X-3

X-4

X-5 X-6

XX-1

XX-2

XX-3

XX-4 XX-5

Helmet Sample X

Helmet Sample XX

Denotes a shot on the ballistic shell

Denotes a shot on or next to hardware

Shot number

25mm from edge

60mm from edge

90mm from edge

100mm

Diameter

Crown area

0˚

180˚

270˚

45˚

135˚225˚

315˚

90˚

OBLIQUITY

HELMET AS

VEIWED FROM

ABOVE

SHOT LOCATION FOR BFD SCORING

Helmet

Denotes FASTNER

REAR

FRONT

RIGHT

SIDE

CENTER OF

100mm

Diameter

Crown area

LEFT

SIDE

15mm 15mm

15mm

15mm

20mm

AMBIENT TEST

Helmets

1-1

1-2

1-3

1-4

1-5 1-6

2-1

2-2

2-3

2-4 2-5

Helmet Sample 1

Helmet Sample 2

WATER CONDITIONED

Helmets

3-1

Helmet Sample 3

Helmet Sample 4

3-2

3-3

3-5

3-4

3-6

4-1 4-2

4-3

4-4

4-5

HOT TEMPERATURE CONDITIONED

Helmets

Helmet Sample 5

Helmet Sample 6

5-5

5-1

5-2

5-4

5-3

5-6

6-1

6-2

6-3

6-4

6-5

Helmets

Helmet Sample 7

Helmet Sample 8

7-1

7-2

7-3

7-4

7-5

7-6

8-1

8-2 8-3

8-4

8-5

COLD TEMPERATURE CONDITIONED