MSA LH 350 User manual

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MAINTENANCE MANUAL
LH 350 FLIGHT HELMET

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Table of Contents
Topic Page
Table of Contents 2/19
WARNING 3/19
DESCRIPTION OF HELMET 4/19
GUARANTEE 5/19
PREAMBLE 6/19
CHINSTRAP 7/19
CLOTHING 8/19
OUTER VISOR 9/19
INNER VISOR 10/19
NVG HARD COVER 11/19
THE INNER IMPACT CAP 12 and 13/19
NECK PAD 14/19
ACCESS TO ELECTRONIC CARD 15/19
ELECTRONIC CARD 16/19
INSPECTION VERIFICATION 17/19
AND MAINTENANCE REQUIREMENTS
MANDATORY INSPECTION 18/19
AND REPLACEMENT CRITERIA

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WARNING
Thank you for placing your trust in MSA products.
Please read these instructions carefully before using your helmet.
Failure to observe these instructions could reduce the amount of protection your
helmet provides.
Your helmet will only provide maximum protection if all of the MSA
components are used with
it. Furthermore, any change made to your helmet or failure to use one of the original
helmet components will imply improper use of the equipment, and will discharge MSA
of any liability.
In an ongoing effort to improve its products, MSA
hereby reserves the right to alter them at no
notice.
To guarantee sufficient protection, the helmet must be adapted and adjusted to the
wearer’s head size.
Your helmet is desig
ned such that the pressure built up when it is knocked is absorbed
by the partial destruction or damage to the outer and inner cap; even if such damage is
not immediately apparent, we recommend replacing any helmet which has taken a
considerable impact.
The user’s attention is also drawn to the dangers of modifying or removing any of the
original components of the helmet, apart from any modification or removal
recommended by the helmet manufacturer. Under no circumstances should helmets be
adapted for attachment of accessories by any means not recommended by the helmet
manufacturer.
Do not apply any paint, solvents, adhesives or self-adhesive labels, other than those
recommended by the helmet manufacturer’s instructions.
The MSA LH 350 flying helmet is designed only for helicopter pilots and crew members. It
ensures a maximum comfort and protection.
Available in three sizes to fit head measuring between 52 cm to 64 cm. It incorporates two
visors; and could receive a wide range of communication systems and Night Vision Goggles
supports, available to order. Please contact us for details.
Each helmet is individually serial numbered to ensure correct identification of the helmet and
a correct record of the service life history of the helmet.
Checks should be made following any apparent impact, carried out by our
maintenance department or a specialist.

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LH 350 F L I G H T H E L M E T
DESCRIPTION OF HELMET
The LH350 helmet shell is made of :
• A one-piece shell in high performance composite fibers. The shell covers a large head
protection zone.
• An expanded polystyrene inner padding for impact absorption. It is covered with a velvet
lining for the user's comfort.
• Custom fit pads are used to fit the helmet to the users headform.
The outside coating is flame retardant.
The inner lining is made up of two comfort spacers : the T shaped spacer and the neck spacer
each of these spacer can be personalized with different foam in 3 thickness (4mm, 8mm and 12mm)
which make it possible to obtain a perfect fit for the user's head form.
The lining elements are made up of different thickness foam inserts covered in a ‘patented‘ wicking
material to draw moisture away from the users skin in hot and humid climates and ensure the user’s
comfort.
These two comfort spacers are attached inside the shell by Velcro strips. Adaptation to the user's
head form is made by choosing the foam thickness inside each spacer.
Two protective visors manufactured are fitted to the LH350 :
• Both visors are mounted on the outside of the helmet shell and fully protected by the hard
cover
• Both visors can be adjusted to suit the users requirements.
The acoustic protection system is made up of :
• Two injection molded thermoplastic earcups, with a recess to accommodate the
communication earphones.
• Two earseals for comfort, ergonomically shaped.
• Specific acoustic foam.
These earcups ensure correct acoustic protection and are fixed inside the shell by Velcro spacers.
The chinstrap is made of a synthetic fire-proof fibre strap with a clipping buckle. A leather chinstrap
covers the strap to ensure user’s comfort at the chin.
8
A helmet protective bag.
Serial Number, Helmet Log Card and Modification Record.
Every MSA flight helmet is supplied with a helmet log card recording the manufacturing and model
details of the helmet, in addition to recording modifications and Level 3 repairs to the helmet.
Each helmet is individually serial numbered to ensure correct identification of the helmet and a
correct record of the service life history of the helmet.

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G U A R A N T E E
All of our models, accessories, and spare parts are meticulously inspected before leaving
the factory.
MSA helmets and their options are guaranteed for one year from the date of purchase.
Guarantee provides for parts and labor repair or replacement of the helmet and components arising
from any mechanical or electrical failure or defect which may occur during normal operating
conditions as described in the helmet Instruction Manual supplied with each helmet.

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PREAMBLE
Important : for any repair install the helmet at least on the helmet protecting bag
Necessary tools :
- 20, 15 and 10 TORX key
- 7 mm combination wrench
- 2 mm hexagonal screw driver
- Flat blade screwdriver
- Threadlocking low strength (LOCTITE 222 or equivalent )

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1. Chinstrap:
Tools: 20 and 15 TORX keys, 7 mm combination wrench and flat blade screwdriver.
Dismantling duration: 1 minute.
Mounting duration: 2 minutes.
Open the chinstrap.
4 points chinstrap disassembly
Left and right chinstrap dismantle:
1 front fixation points: unscrew the outer screw with the 20 key TORX while maintaining inner
helmet nut with 7 mm combination wrench (remove the nut cap with the screw driver before ),
2 rear fixation points : unscrew the inner helmet screw with the 15 TORX key.
Proceed in the reverse order to reassemble.
Warning: Apply Threadlocking low strength on the inner TORX screw back fixation point before
mounting.
When removing the chin-cup; check that the buckle is correctly positioned, the opened side of
the buckle towards the outside of the helmet.
20 TORX
key
7 mm combination
wr
ench
15 TORX key
1
Inside detail
Inside detail
2

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2. Clothing:
Tools: none.
Dismantling duration: 20 seconds.
Mounting duration: 45 seconds.
LH 350 helmet includes 2 comfort parts and spacers:
• 1 adjustable, comfortable T-shaped spacer with 4 mm, 8mm and 12mm thick foam,
•
Comfort neck spacer with 4 mm, 8mm and 12mm thick foams,
• Self-gripping spacers for ear cup adjustment.
Those elements are fixed inside the helmet by self gripping tapes.
When changing the foam in the T shaped spacer and in the comfort neck spacer, insure that the
chosen foams are well positioned. Check the presence of the trapezoid insert with the comfort
neck spacer.
4mm thickness foam (no hole)
8mm thickness foam (1 hole)
12mm thickness foam (2 holes)

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3. Outer visor :
Tools : none.
Dismantling duration: 2 minutes.
Mounting duration: 2 minutes.
Unscrew the 2 captive screws on the right and left sides.
Raised the hard cover by rotating back side the hinge.
Remove the outer visor by sliding outside the hard cover
Proceed in the reverse order to reassemble.
Warning
When replacing the hard cover, ensure that the lug is securely in place beneath the base. See
below.
Screw up the captive screws on the right and left sides.
lug
Opened position
Closed position
hinge

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4. Inner visor :
Tools : none.
Dismantling duration: 2 minutes.
Mounting duration: 2 minutes.
Lower the inner visor
Unscrew the 2 captive screws on the right and left sides.
Raised the hard cover by rotating back side the hinge
.
1- Open the left and right base covers by rotating upwards
(do not unscrew anything).
2- Disengage the visor interfaces from their axis of rotation.
Proceed in the reverse order to reassemble.
Warning
When replacing the hard cover, in closed position, ensure that the lug is securely in place
beneath the base.
lug
Screw up the captive screws on the right and left sides.
1
2
visor interface
base cover
hinge
Opened position
Closed position