54-01-01 HAMILTON STANDARD: Applies to All Hamilton Standard Reversing Propellers Models 43D, 43E, 34D, 34E, 232 and 242.
Compliance required as indicated.
Subsequent to December 31, 1954, Hamilton Standard Model 67000 reverse solenoid valves shall not be used on civil aircraft.
Analysis has shown that unwanted reversal of Hamilton Standard propellers could possibly occur with use of the Hamilton Standard Model 67000 reverse solenoid valve if any of the following malfunctions of the valve were experienced:
1. A broken plunger spring. This could cause the valve to open fully.
2. A film of oil between the armature and the valve body. This could cause the valve to remain fully open.
3. A foreign particle lodged between the valve and its seat. This could cause a pressure buildup in the reverse oil passage.
Although there is no record of such malfunctions of this valve on civil aircraft, the potential hazards that exist indicate the desirability of precluding future use of this obsolete component.