Improperly secured propeller cables can cause major damage to engine beams.
The FAA issued Exhaust AD 2000-01-16 regarding potential exhaust damage and applicable inspections of engine beams. It applies to the majority of all Cessna piston twin aircraft.
In that AD, the significance of engine beam damage from exhaust leaks is made clear, yet similar critical damage can also be taking place due to the wear caused by propeller cables. While performing the exhaust damage inspections, it is a good time to check for propeller cable wear.
Care taken when installing a propeller cable can help avoid expensive future damage - requiring an engine beam replacement.
RAM Service Managers have seen several incidents of propeller cable related beam damage on aircraft arriving at RAM for engine installations. The stainless steel cable housing can cut / saw completely through the engine beam if left neglected long enough. [ See photo ] This kind of damage can require replacement of the entire beam, costing thousands of dollars.
Help avoid this damage opportunity. Properly securing the propeller cable during initial installation is essential. The use of a firesleeve over the cable housing will also help protect the beam and prolong the life of the cable. Even with a firesleeve installed, the entire cable crossing and sleeving should be recurrently checked and corrected as necessary.