Gentex HGU-84/P Troubleshooting guide

OPERATION AND MAINTENANCE INSTRUCTIONS
WITH ILLUSTRATED PARTS LIST
HGU-84/P COMMERCIAL
HELMET ASSEMBLY
GENTEX CORPORATION
CARBONDALE, PA
JUNE 2001
© 2001 GENTEX Corporation

CONTENTS
CHAPTER 1: INTRODUCTION AND GENERAL INFORMATION
1-1 INTRODUCTION ....................................1-1
1-2 SCOPE ........................................1-1
1-3 SYSTEM DESCRIPTION ................................1-1
1-3.1 HELMET ASSEMBLY.............................1-1
1-3.2 HELMET SHELL ASSEMBLY ........................1-2
1-3.3 THERMOPLASTIC LINER ASSEMBLY (TPL®) ASSEMBLY ........1-2
1-3.4 EARCUP ASSEMBLIES ...........................1-3
1-3.5 INTEGRATED CHIN/NAPE ASSEMBLY ...................1-3
1-3.6 EEK-4 SINGLE VISOR ASSEMBLY .....................1-4
1-3.7 DUAL VISOR ASSEMBLY WITH QUICK DISCONNECT ..........1-4
1-3.8. LIGHTWEIGHT VISORS ...........................1-4
CHAPTER 2: PREPARATION FOR USE
2-1 SIZING ........................................2-1
2-2 HELMET FITTING ...................................2-2
2-3 FITTING OF TPL ASSEMBLY .............................2-5
2-4 FITTING OF OPTIONAL BAYONET RECEIVER ASSEMBLY ............2-9
2-5 INSTALLATION OF LIGHTWEIGHT VISORS ....................2-12
2-6 ANVIS MOUNT MODIFICATION (DUAL VISOR ASSEMBLY) ...........2-13
CHAPTER 3: MAINTENANCE
3-1 GENERAL........................................3-1
3-2 INSPECTION ......................................3-1
3-2.1 Preflight/Postflight Inspection .........................3-1
3-2.2 Calendar Inspection..............................3-1
3-2.3 Visual Inspection ...............................3-2
i

CONTENTS (Continued)
3-3 CLEANING .......................................3-3
3-4 SERVICING THE HELMET...............................3-4
3-4.1 INSPECTION UPON RECEIPT........................3-4
3-4.2 REPLACEMENT OF COMPONENTS ....................3-5
3-4.2.1 Replacement of TPL Cover or Layer Assembly.............3-6
3-4.2.2 Replacement of Earcup Assembly or Earphone ............3-7
3-4.2.3 Replacement of Earphone Holder ...................3-9
3-4.2.4 Replacement of Earseal ........................3-10
3-4.2.5 Replacement of Chin/Nape Strap Assembly .............3-11
3-4.2.6 Replacement of Chin Strap and Chin Pad...............3-13
3-4.2.7 Replacement of Nape Strap Clamp ..................3-14
3-4.2.8 Replacement of Boom Swivel Assembly ...............3-14
3-4.2.9 Replacement of Optional Bayonet Receiver Assembly ........3-16
3-4.2.10 Replacement of Energy-Absorbing Liner...............3-18
3-4.2.11 Replacement of Dual Visor Assembly ................3-20
3-4.2.12 Replacement of Single Visor Assembly ...............3-22
3-4.2.13 Replacement of Visor Lock Assembly ................3-24
3-4.2.14 Replacement of Single Visor Lens ..................3-25
3-4.2.15 Replacement of Lightweight Visor ..................3-26
3-4.2.16 Replacement of Visor Snap .....................3-27
CHAPTER 4: ILLUSTRATED PARTS BREAKDOWN
4-1 GENERAL .......................................4-1
4-2 COMPONENTS OF IPB ................................4-1
4-2.1 Figure and Index Number Column ......................4-1
4-2.2 Part Number Column .............................4-1
4-2.3 Description Column ..............................4-1
4-2.4 Units Per Assembly Column .........................4-1
4-2.5 Usable on Code Column ...........................4-1
ii

CHAPTER 1
INTRODUCTION AND GENERAL INFORMATION
1-1 INTRODUCTION
The HGU-84/P Commercial Helmet Assembly is designed to provide eye, ear, and head
protection when properly assembled and fitted to the aircrew member. It has a light-
weight helmet shell constructed of graphite, ballistic nylon, fiberglass, and epoxy resin.
The helmet assembly, available in four sizes (medium, large, X-large, and X-large
wide), is form-fitted. Its stability is enhanced by an integrated chin/nape strap assembly.
The helmet assembly also houses the headset communications and allows for the use
of clear or sunshade visor assemblies. The helmet is designed to permit the use of the
MBU-17/P oxygen mask if required.
1-2 SCOPE
This manual contains a description of the HGU-84/P Commercial Helmet Assembly
as well as the sizing, fitting, and maintenance instructions required to outfit aircrew
members successfully and to maintain the equipment properly.
1-3 SYSTEM
DESCRIPTION
1-3.1 HELMET ASSEMBLY
The aircraft helmet
assembly is available
with one of the
following visor
configurations: (1) a pair
of lightweight visors,
(2) a single visor
assembly, or
(3) a dual visor assembly
with a quick-disconnect
for night vision goggles.
These configurations
are shown in Figure
1-1. A chin/nape
strap assembly and a
thermoplastic liner
assembly are added
to the helmet shell
assembly for a better
fit and increased
stability.
1-1
Figure 1-1. HGU-84/P Commercial Helmet Assembly
HELMET WITH
SINGLE VISOR ASSEMBLY
HELMET WITH
DUAL VISOR ASSEMBLY
(QUICK DISCONNECT)
HELMET WITH LIGHTWEIGHT VISORS

1-3.2 HELMET SHELL
ASSEMBLY (Figure 1-2)
The helmet shell assembly
is intended to provide head
protection during in-flight
buffeting and emergencies
such as ejection, bailout,
or crash landings. It has a
polystyrene energy-absorbing
liner and a fitted leather
edgeroll installed. Earshell
pile fasteners on each side
of the helmet interior help
hold earcups in place. A
boom swivel on the left side
(as worn) of the helmet shell
allows for the mounting of a
boom/microphone assembly.
Optional bayonet receivers
(not shown) can be installed
to hold an oxygen mask.
1-3.3 THERMOPLASTIC
LINER (TPL®) ASSEMBLY
(Figure 1-3)
The TPL assembly, used in
conjunction with the energy-
absorbing liner installed in the
helmet shell assembly, pro-
vides helmet stability and
comfort. The TPL assembly
consists of preformed
plastic layers and a washable
cloth cover, which are held
together by double-sided tape.
If necessary, the TPL assem-
bly can be custom-fitted to the
aircrew member’s head. The
TPL assembly comes in three
sizes: medium, large, and
extra large.
1-2
HELMET SHELL
ENERGY-ABSORBING
LINER
EDGEROLL
EARSHELL PILE
FASTENER
BOOM
SWIVEL
Figure 1-2. Helmet Shell Assembly
Figure 1-3. TPL Assembly
TPL® is a registered trademark of GENTEX
Corporation.
DOUBLE-SIDED
TAPE
PLASTIC LAYERS
CLOTH COVER

1-3.4 EARCUP ASSEMBLIES
(Figure 1-4)
The earcup assemblies provide sound
attenuation and are compatible with
H-87B/U and H-143 earphones.
These assemblies are attached via
hook fasteners to the pile fasteners
installed inside the helmet shell. A
raised-ring earseal on each earcup
optimizes comfort and sound
attenuation. Earcup fitting pads
can be placed between earcup and
fitting shell if needed to optimize
the fit to the aircrew member’s
head. The pads can be cut to
any size or shape.
1-3.5 INTEGRATED CHIN/NAPE
ASSEMBLY (Figure 1-5)
The integrated chin/nape assembly is
adjusted via the chinstrap, which simul-
taneously adjusts the cross straps at the
nape strap area. This provides a snug,
comfortable fit with maximum helmet
stability. Clamp assemblies on the
nape straps allow adjustment of
the nape area without added strain
on the chin strap. The nylon
webbing nape straps feature
a leather-covered pad for comfort. A
spacer pad can be added behind the
nape pad for increased snugness.
The nylon webbing chin strap is
reinforced with aramid tape on the
inside. A snap tab on the right side
(as worn) of the chin strap allows for
fastening and unfastening without the
need for repeated lacing through the
D-rings on the left side (as worn).
The chin strap features a chinpad
with a pile fastener tab. A hook
fastener on the end of the chin strap
fastens to the pile tab to minimize
slippage.
1-3
CHINPAD
D-RING
CLAMPS
NAPE STRAP
SPACER PADS
NAPE PAD
CHINSTRAP
Figure 1-4. Earcup Assembly
Figure 1-5. Integrated Chin/Nape
Assembly
SPACER
PADS
EARCUP
GROMMET EARSEAL
EARPHONE
HOLDER

1-3.6 EEK-4 SINGLE VISOR
ASSEMBLY (Figure 1-6)
The EEK-4 is a single-lens helmet
visor assembly. When installed, the
EEK-4 provides face and eye
protection from impact, projectile
penetration, sun glare, dust,
windblast, and fire. Each assembly
comes with interchangeable clear
and neutral gray (sunshade) lenses.
The installed visor is operated by a
center lock mechanism.
1-3.7 DUAL VISOR ASSEMBLY
WITH QUICK DISCONNECT
(Figure 1-7)
The dual visor assembly has a clear
lens and a neutral gray (sunshade)
lens. The outer lens is operated
via a rotating lock. The inner lens
is operated via an actuating knob.
The center of the housing has a
quick disconnect for ANVIS night
vision goggles. Before you can
use the quick disconnect, you must
attach the ANVIS modification kit to
the ANVIS mount. This procedure
begins on Page 2-13.
1-3.8 LIGHTWEIGHT
VISORS (Figure 1-8)
The lightweight visors protect the
eyes. They are attached and
removed via snap fasteners.
Included are a clear visor and
a neutral gray (sunshade) visor,
both of which are trimmed to
accommodate the MBU-12/P
oxygen mask. Bump stops
attached to the helmet shell
hold the raised visor in place.
A lens cover can be added to
protect the raised visor.
1-4
LOCK MECHANISM
Figure 1-6. EEK-4 Single Visor Assembly
Figure 1-7. Dual Visor Assembly
With Quick Disconnect
Figure 1-8. Snap-On Visors
SNAP
FASTENER
LENS COVER
BUMP
STOP
ACTUATING KNOB
VISOR LENS
QUICK
DISCONNECT
TAB
LOCK
VISOR
HOUSING

CHAPTER 2
PREPARATION FOR USE
2-1 SIZING
To select the proper size helmet shell assembly
for the aircrew member, proceed as follows:
NOTE
Ideally, aircrew members will wear the
same size helmets as in previous
designations. However, if a good fit is
not possible, additional sizing procedures
may be required.
1. If helmets are available, aircrew member
should trial-fit to determine correct size to be
ordered. If helmets are not available, mea-
sure the circumference of the head with a
tape measure as shown in Figure 2-1. Refer
to Table 2-1 as a guide for sizing.
NOTE
Sizing instructions are provided only as general guidance. Because of the
wide variation in head shapes likely to be encountered, it is not possible to
present detailed guidance. The helmet is designed to provide lightweight
head protection and should fit close to the head. For this reason, aircrew
members should be fitted with the smallest helmet size that provides an
acceptable fit.
2. Once the correct size has been determined, requisition the helmet shell assembly
through normal supply channels.
Table 2.1. HELMET SHELL ASSEMBLY SIZING GUIDE
CIRCUMFERENCE (INCHES/MILLIMETERS) SHELL AND LINER SIZE REQUIRED
Less than 21-1/2 in. (546 mm.) Medium
21-1/2 to 22-1/2 in. (546 to 571 mm) Large
22-1/2 to 23-1/2 in. (571 to 596 mm) or more X-Large
23-1/2 in. (596 mm) or more X-Large Wide
2-1
Figure 2-1. Head Circumference
for Helmet Sizing

2-2. HELMET FITTING
1. Place the TPL in the helmet, ensuring that the holes in the TPL plastic layers are
positioned toward the front of the helmet.
NOTE
The TPL should seat down against, and align with, the front edge of
the energy-absorbing liner.
2. Have the aircrew member don the helmet as follows:
CAUTION
Spread the helmet just enough to allow ease of donning and doffing.
Excessive spreading may damage the helmet.
a. Grasp the helmet with thumbs hooked in the earcups, and spread the helmet
slightly.
b. Place the front edge of the helmet against the forehead.
c. Rotate the helmet toward the rear and down onto the head. Ensure that the
edgeroll is positioned just out of the aircrew member’s line of sight as the aircrew
member looks upward.
3. Check earcup position, ensuring that the earseals completely surround the ears.
4. Check earseal compression.
For optimum sound attenuation,
earseals should be compressed
to about half of their original
thickness. If necessary, adjust
compression by adding earcup
spacer pads.
NOTE
The earcup spacer pads
can be installed whole or
trimmed to any size or
shape needed for optimum
earseal compression.
Figure 2-2 shows several
examples.
2-2
INCREASE
OVERALL
PRESSURE
Figure 2-2. Earcup Spacer Pad Trims
BALANCE
TOP/BOTTOM
PRESSURE
BALANCE
FRONT/REAR
PRESSURE
BALANCE TOP/BOTTOM
AND FRONT/REAR
PRESSURES
BALANCE
CORNER
PRESSURE

5. Loosen the chinstrap clamp screws,
and slide the clamps (Figure 2-3)
down as far as possible on the
chinstrap. Adjust the nape straps for
a snug fit. Slide the clamps to hold
the adjusted straps in place, and
tighten the screws.
6. If you cannot achieve a snug fit by
adjusting the nape strap clamps,
install spacer pads (supplied with
the helmet) as needed between
the nape pad and the TPL.
7. If not already done, insert the
end of the chinstrap (Figure 2-4)
through the D-ring on the right side
(as worn) and fasten the snap.
8. Have the aircrew member
fasten the chinstrap as
follows (Figure 2-4):
a. Feed the end of the chinstrap
through the D-rings on the left
side of the helmet (as worn).
b. Split the D-rings, and loop the
end of the chinstrap through
the inner D-ring.
c. Tighten the chinstrap to the desired
tension. Thereafter, fasten and
unfasten the chinstrap via the
snap on the right side (as worn)
of the helmet.
9. Slide the chinpad (Figure 2-4)
to the center of the chinstrap.
Using needle and thread,
tack the chinpad in place to
prevent slippage.
2-3
Figure 2-3. Chinstrap Clamps
INNER
D-RING
END OF
CHINSTRAP CHINPAD
Figure 2-4. Fastening Chinstrap
CLAMP
CLAMP