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

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5. NVG hard cover :
Tools : 2 mm ALEN screw driver.
Dismantling duration: 2 minutes.
Mounting duration: 3 minutes.
Unscrew the 2 captive screws on the right and left sides .
Unscrew the 2 ALEN screws on the hinge.
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.
.
lug
Screw up the captive screws on the right and left sides
Opened position
Closed position

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6. The inner impact cap:
Tools : 15 TORX key
Dismantling duration: 5 minutes.
Mounting duration: 8 minutes.
To dismantle the inner cap :
- remove all the comfort parts (T spacer, neck spacer),
- remove the two ear cups,
- dismantle the chinstrap (see chap. 2),
Remove the stud
Remove the in
ner left and right
inner padding
15 TORX key
Remove the blocking pieces
on each side of the shell
Inner detail
Remove the
neck pad

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Pull the rear side of the inner impact cap to release
the inner cap of the shell
Then pull the front part of the inner cap
Proceed in the reverse order to reassemble.
Warning for neck pad mounting see § 7.

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7. Neck pad mounting :
Tools: 2 mm ALEN screw driver,
Mounting duration: 1 minutes.
Inside the shell : insert the 2
clamps of the neck pad in the
electronic card support seating.
Outside the shell, screw the 4 screws with 2 mm ALEN screw driver.
Outside the shell, partly unscrew the 4
screws with 2 mm ALEN screw driver.

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8. Access to the electronic card:
Tools: 2 mm ALEN screw driver, 15 TORX key
Dismantling duration: 3 minutes.
Mounting duration: 4 minutes.
Proceed in the reverse order to reassemble.
Remove the cover to have access
to the electronic card
Unscrew the cable maintain
screw with the 15 TORX key.
Unplug the cable plug
on the card.
Remove the cable for a complete access
to the electronic card.
Unscrew the 4 screws with 2 mm
ALEN screw driver

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9. Electronic card
Tools : flat blade screwdriver
Dismantling duration: 1 minute.
Mounting duration: 2 minutes.
See § 8 for access to electronic card.
Unplug the 3 JST plugs
Left earphone
Right earphone
Microphone.
Pull out the card with the flat
blade screwdriver screw driver as shown.
Proceed in the reverse order to reassemble.
Left
earphone Right
earphone
Microphone

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10. Inspection, Verification and Maintenance Requirements.
The MSA range of flight helmets is designed as a modular solution to meet the
requirements of helicopters pilots and crew members. The helmet is designed to
require minimal maintenance intervention and recommended servicing or repair is on
an ‘ON CONDITION BASIS’.
Accordingly, a full periodic service program is not recommended or required in
support of the LH350 flight helmets.
Listed below is a recommended schedule of servicing which may be adopted by
users of the LH350 flight helmet.
MSA do not recommend a program of servicing which involves complete
disassembly of the helmet on a periodic basis.
The helmet is designed and engineered to enter and remain in operational service
until such time as corrective maintenance is required for unserviceabilities of the
helmet shell, visor system or communications package.
Inspection, Verification and Maintenance Matrix:
Basic Controls*
Before each flight
Cleanness and working of the visors Yes
Attendance of the comfort pads Yes
Chinstrap status working and fixation points Yes
Functional check of communications Yes
Hard cover fixation points Yes
Fixation points of electronic box Yes
Periodic Controls* Every:
Tightening and working of: inner and outer visors, communication
system, anti cable tear-out system 3 months
State of the visors and fixation system 3 months
State of the pads 3 months
State of comfort ear set 3 months
State of the chin strap and working of the locking system 3 months
State of the shell (single impact use) 3 months
Cleaning as specified in User Manual 2 months
Major Spare Parts Replacement* (Forecast Replacement
Interval) Every:
Inner visor 5 years
Outer visor 5 years
TSHAPED SPACER NECK PAD SPACER 2 years
Comfort ear seal
Chinstrap 2 years
Inner cap 5 years
Shell 10 years
Note: Inspection criteria based on a standard 200 hours annual usage period.

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11. Mandatory Inspection & Replacement Criteria
This section details the mandatory actions and inspections required when a helmet suffers a
confirmed impact incident OR when routine maintenance reveals damage consistent with an
impact incident.
Mandatory actions and inspection requirements are detailed in the matrix listed below.
Mandatory Inspection & Replacement Criteria Matrix:
ACTION TO BE TAKEN
Condition
Mandatory Replacement Requirement – Confirmed
Impact:
The helmet shell is designed for single impact use ONLY.
• The helmet shell and protective integrity is considered
compromised following a confirmed impact;
• The helmet shell is to be removed from service immediately
following a confirmed impact and rendered unusable or
destroyed.
CONFIRMED
IMPACT
Mandatory Inspection Requirement Unconfirmed
Impact:
Where damage consistent with helmet impact is displayed. The
helmet is to be inspected for the following;
• Indentation, cracking or deformation of the composite fibers
shell and hard cover;
• Damage to the composite shell construction including cut or
frayed fibers;
• Removal of outer protective coating resulting in the
degradation of the gel coating exposure of composite fibers;
• Dislodgement or deformation of the impact cap;
• Damage to the visor adjustment and rotation mechanisms;
• Damage to the chinstrap webbing, buckle assembly and
fixation points;
• Inspection to be recorded on helmet log card.
If damage consistent with an impact is confirmed - Mandatory
Replacement is required.
Mandatory
Inspection if
Impact
Suspected
User & Operational Maintenance Responsibility
All helmet users and operational maintenance units are responsible for reporting
known or suspected impact incidents and damage to helmet shells. Operational
maintenance units are responsible for ensuring the required inspection criteria are
met in assessing the continued serviceability of the helmet.
Failure to withdraw a damaged helmet shell from operational use will relieve MSA
from any liability in the event of helmet failure.