AD 50-34-01 ACTIVE

50-34-01 KOPPERS: Applies to All Aircraft Equipped With Model F200 "Aeromatic" Propellers (Does Not Apply to "Aeromatic Model 220 Propellers").

Compliance required in all cases no later than April 1, 1952.

1. Universal (Stinson) Models 108-2 and 108-3 aircraft: Compliance required no later than first 200 hours of propeller operation.

2. Universal (Stinson) Models 108 and 108-1 aircraft: Compliance required no later than first 400 hours of propeller operation.

3. If the total propeller operation time is unknown, or if a reasonably accurate estimate of total time cannot be made, compliance is required not later than the next 50 hours of operation. (Except for Universal (Stinson) Series aircraft, compliance is required by not later than the next 50 hours of operation if the total operation time as of August 29, 1949, exceeds 500 hours.)

Blade retaining flanges, P/N 3277 must be replaced with P/N 3277-1. When this change is accomplished a "-1" (dash one) is tobe suffixed to the propeller assembly number on the nameplate to indicate compliance. Koppers Service Bulletin No. 24 covers this same subject.

Universal (Stinson) Models 108-2 and 108-3 only: (Compliance required by May 16, 1949). To avoid the possibility of crankshaft or propeller failures resulting from excessive torsional vibration in the 2,700 to 2,800 r.p.m. range, all engine operation must be restricted to 2,650 r.p.m. maximum and propeller readjusted in accordance with Koppers Service Bulletin No. 22. As a further safety measure it is required that propellers which have accumulated any operating time in the 2,650 to 2,800 r.p.m. range be equipped with new blade retainer flanges P/N 3277-1.

(Koppers Service Bulletin No. 23-E covers this same subject.)

This supersedes AD 49-42-01, for the purpose of clarifying the date of compliance.