A Cessna T207A aircraft, with seven persons on board, was departing Jabiru for a local scenic flight. The operator reported that the control rod end for the right aileron disconnected and the aileron deflected upwards shortly after the aircraft had rotated for takeoff. The takeoff was continued as there was insufficient runway remaining to stop the aircraft. A significant amount of left aileron input was then required to counteract the tendency for the aircraft to roll right. The pilot was able to conduct a normal left circuit and landed the aircraft safely at the departure runway. There were no injuries to passengers or crew, and no damage to the aircraft.
The investigation found that the swivel joint for the rod end, which attached to the outboard end of the right aileron control rod, had fractured and separated at the base of the threaded section. The rod-end fitting consisted of a rounded but flat-sided cast-alloy housing with a threaded tail section, which was attached to the interconnecting drive rod from the wing. The housing contained a spherical bearing with a bolt through the centre (at ninety degrees to the threaded tail) which connected the drive rod to the aileron control surface.
Metallurgical examination confirmed that the rod-end bearing had seized in the housing due to surface corrosion on the sliding surfaces. That action had exposed the threaded shank section of the fitting to elevated bending loads, rather than the push-pull loads for which it was designed. Cracking then initiated and propagated, through about 50% of the rod-end cross section, under normal operating conditions over an extended period before finally separating.
Examination of the maintenance documentation for the aircraft showed that the failed rod end was fitted to the aircraft as a new item on 14 Oct 1999. The rod end failed in service on 13 June 2001. At that time it had completed a total of 754.3 hours time-in-service. The rod ends did not have a time-in-service life and were listed by the manufacturer as an "on condition" item.
The company reported that it had a policy of changing all control rod swivel-end fittings when their aircraft underwent repainting; approximately every 4-5 years. The investigation was unable to determine why the rod end was not changed at the last repaint.
Local safety action
The operator reported that, to ensure integrity, they had conducted an inspection of all flight control rod ends for the company fleet of aircraft.
|Date:||10 June 2001||Investigation status:||Completed|
|Time:||1628 hours CST|
|State:||Northern Territory||Occurrence type:||Flight control systems|
|Release date:||14 March 2002||Occurrence class:||Technical|
|Report status:||Final||Occurrence category:||Incident|
|Highest injury level:||None|
|Aircraft manufacturer||Cessna Aircraft Company|
|Type of operation||Charter|
|Damage to aircraft||Nil|
|Departure point||Jabiru, NT|
|Departure time||0658 hours CST|