TM 5-4220-225-14
Table 4-1. Unit Troubleshooting Procedures (Cont).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
10. EXCESSIVE OR UNCONTROLLABLE FLOW (Cont).
Step 3. Remove the supply valve handle and valve stem. Inspect for foreign matter between valve
stem and valve seat.
Clean the valve assembly and check the air supply system for further fouling.
Determine source of the fouling material. Ensure air flow can be reduced.
Step 4. Inspect valve stem for damage.
Replace valve stem (para. 4-21).
11. IMPROPER HELMET P.
Step 1. Attempt to operate the poppet valve with chin button.
Clean and lubricate the poppet shaft and mounting hole. Replace the poppet
valve or the exhaust valve body if necessary (para. 4-23 or 4-24). Reassemble
and perform helmet flow and P test (para. 2-8).
Step 2. Remove the poppet valve assembly and inspect the valve shaft and its mounting hole for
dirt or corrosion.
Clean and lubricate the poppet shaft and mounting hole. Replace the poppet
valve or the exhaust valve body if necessary (para. 4-23 or 4-24). Reassemble
and perform helmet flow and P test (para. 2-8).
Step 3. Inspect the exhaust valve diffuser for dirt, salt encrustation, and oil.
Replace or clean and reinstall the diffuser (para. 4-23 or 4-24). Perform helmet
flow and P test (para. 2-8).
Step 4. Check exhaustvalve for proper operating range by performing helmet flow and P test
(para. 2-8).
Replace the exhaust valve spring (para. 4-23 or 4-24) and readjust the exhaust
valve during retest (para. 2-8).
4-9
