Summary
The FAA proposes to adopt a new airworthiness directive (AD) for McCauley Propeller Systems models 3A32C406/82NDB-X and D3A32C409/ 82NDB-X propellers, installed on Teledyne Continental Motors (TCM) IO- 520, TSIO-520, or IO-550 reciprocating engines. These propellers are herein referred to as C406 and C409 propellers, respectively. This proposed AD would require adding an operational revolutions per minute (rpm) restriction on the C406 and C409 propellers, and installing an rpm restriction placard in the cockpit. This proposed AD would also add a 10,000-hour total time-in-service (TIS) life limit for these propellers. This proposed AD would also remove from service any propeller that has 10,000 hours or more total TIS, or that has an unknown total TIS. Also, this proposed AD would require initial and repetitive propeller blade inspections for damage, and repair if necessary. This proposed AD results from testing by the manufacturer that identified stress conditions that affect the fatigue life and damage tolerance of C406 and C409 propellers, when installed on TCM IO- 520, TSIO-520, or IO-550 reciprocating engines. We are proposing this AD to prevent blade or hub failure that could result in separation of a propeller blade and loss of control of the airplane.