TM 3-4240-212-14&P
CHAPTER 3
OPERATOR' MAINTENANCE
S
Section I. TROUBLESHOOTING
Table 3-1. Operator's Troubleshooting Procedures
WARNING
Return to fresh air before investigating or
Malfunction
correcting any malfunctions.
test or inspection
corrective action
3-1.
Scope
1. AIR IN FACEPIECE IS ODOROUS OR IRRITATING
a. This section contains troubleshooting or
Step 1.
Check breathing tube couplings.
malfunction information and tests for locating and
Step 2. Inspect breathing tube for defects. Notify
correcting most of the troubles which may develop in the
M20 breathing apparatus Each malfunction or trouble
higher maintenance of defects.
symptom for an individual component, unit, or system is
Step 3. Inspect pressure relief valve for defects. Notify
followed by a list of tests or inspections necessary for you
higher maintenance of defects.
to determine probable causes and suggested corrective
Step 4. Inspect breathing bag for tears or damage.
actions for you to remedy the malfunction.
Notify higher maintenance of defects.
b.
This manual cannot list all possible
Step 5. Inspect canister handwheel. Tighten
malfunctions that may occur or all tests or inspections,
handwheel.
and corrective actions If a malfunction is not listed
2. BREATHING RESTRICTED
(except when malfunction and cause are obvious), or is
Step 1. Make sure breathing bah is not overinflated.
not corrected by listed corrective actions, you should
Release pressure, paragraph 2-5 .
notify higher level maintenance.
Step 2. Make sure canister is not depleted. Install new
c.
canister, paragraph 2-2c and d.
you may find during the operation or maintenance of the
Step 3. Inspect facepiece valve assembly for defects.
M20 breathing apparatus or its components You should
Notify higher maintenance of defects.
perform the tests /inspections and corrective actions in
3. LENSES FOG
the order listed.
Step 1. Make sure canister is not depleted. Install new
NOTE
canister, paragraph 2-2c an d.
Before you use this table, be sure you have
Step 2. Check ambient temperature. Use antifogging
performed all normal operational checks. If you
cloth if temperature is below freezing.
have a malfunction which is not listed in this table,
4. TIMER DOES NOT RING
notify the next higher level of maintenance.
Step 1. Inspect timer for defects.
Notify higher maintenance of defects.
Section II. MAINTENANCE PROCEDURES
will stretch out of shape If forced over the top of the head.
3-2. Testing Pressure Relief Valve
c. Make sure that head-harness straps lie flat
a. Depress and release pressure relief valve stem
against the head and that the head-harness pad is
to see that valve operates freely.
centered on the back of the head.
b. Report defects to organizational maintenanc
e
d. Adjust harness straps so that facepiece fitssnugly
personnel.
and comfortably against the face, and that the lenses are
positioned properly for good visibility
3-3. Adjusting and Testing Facepiece Group
e. Place hand around housing clamp Move the
a. Disconnect breathing tubes from backplate
facepiece from side to side to adjust It snugly against the
assembly.
face. Take up looseness by readjusting
b. Don facepiece as follows grasp facepiece
between thumb and fingers, Insert chin, and gently push
head harness over the top of the head. The head harness
3-1
