AWB 61-2 Issue 1, Hartzell - Feathering Propeller Air Charge Reduction. HC-SL-61-197
Hartzell - Feathering Propeller Air Charge Reduction. HC-SL-61-197
AWB 61-2 Issue 1, 23 October 2001
Aircraft fitted with Hartzell feathering propellers that use an air charge within the propeller cylinder to feather the propeller.
To advise operators and aircraft maintenance organisations that the information contained in HC-SL-61-197 is considered approved data in accordance with CAR 2A, and to be used to maintain the propeller / aircraft combinations listed in the Service Letter, until the applicable maintenance manuals are revised.
The propellers fitted to the aircraft as listed in the Service Letter, have experienced instances of inadvertent feathering. These events have occurred either at the time of shutdown or at low engine RPM. Hartzell have determined that this tendency may be reduced or eliminated by lowering the pressure of the air charge within the propeller cylinder. Hartzell advise that the FAA has approved the technical data in Service Letter HC-SL-61-197 that affects type design.
CASA therefore recommends that operators and aircraft maintenance organisations follow the instructions contained in Hartzell HC-SL-61-197. Hartzell advise that compliance with this Service Letter is not mandatory until the affected propeller is overhauled, and may be accomplished at the convenience of the operator before that time. When the pressure is lowered, however, new decals are to be installed as described in the text of Service Letter HC-SL-61-197.