Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 30; Flight Crew Total 1100; Flight Crew Type 542
Situational Awareness
Aircraft Equipment Problem Critical; Inflight Event / Encounter Object
Aircraft Aircraft Damaged; Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed
Aircraft
During initial climbout; I heard a rattling noise and as I looked around to find the source of the noise; I found that the piano hinge rod on the right side of the cowling had slid its way forward; toward the rear of the propeller. I immediately reduced power and turned back towards the field at about 1;500 FT AGL. The other two aircraft in my flight continued on with their flight plan. The Husky I was flying was equipped with an MT composite two blade; 80 inch propeller. I reduced power and turned back towards the airport. As I started my descent the propeller automatically started to increase the blade angle to try to keep the prop below redline; bringing the trailing edge of the prop into contact with the protruding rod. The rod oscillated violently a few times as it struck the trailing edge of the propeller. At the time I thought the rod was simply being affected by the vibrations in the cowling. I landed and shut down and assessed the damage. The affected area was about 3.5 to 4 inches wide and about .75 to 1 inch deep on each trailing edge of each blade. The rod wasn't bent but had chewed its way past the fiberglass and into the wooden layers of the propeller. There was no sign of the hinge pin protruding during the pre-flight inspection. This could easily have been avoided by simply adding two 90-degree bends on the fore and aft ends of each hinge pin.
Reporter stated his Aviat A-1C-Husky is approximately five years old and uses a constant speed; two bladed composite propeller made with laminated wood; wrapped in a fiberglass shell with a metal strip on the leading edge. A steel hinge pin is used at the top of the left and right engine cowling. The cowling is made from thin aluminum; approximately .030' thousandths of an inch thick. Reporter stated that the aircraft Manufacturer's procedures are to strike the forward and aft ends of each hinge pin causing the pin to swell at the ends and prevent movement of the pin. On his Husky; the right hinge pin did not seem to have any swelling (pinching) at the forward end. What causes the hinge pin to migrate forward is unclear. There was substantial damage to the prop near the blade root; hub area. Not only was he concerned about the propeller; but he noticed gaps developing at the aft hinge section of the cowling; as the hinge pin migrated forward; raising more concerns the right cowling might separate or start to tear away in flight. On the ground; the hinge pin was easily pushed back into the hinge assembly and squeezed down (crushed) at the forward end to prevent further movement.
A pilot flying an Aviat A-1C-Husky aircraft hears a rattling noise and notices the piano hinge on the engine's right cowling migrating forward and cutting into the trailing edge of the composite propeller. Gaps had also developed at the aft hinge section as the hinge pin continued migrating forward; raising further concerns the cowling might start to tear from the aircraft.