Aircraft: Piper Seminole. Injuries: None. Location: Lawrenceville, Ga. Aircraft damage: Substantial.
What reportedly happened: A CFI and pilot receiving instruction were practicing power-off stalls. While configuring the airplane, the pilots noted that after selecting the gear down position there was an unsafe gear indication.
The CFI made several unsuccessful attempts to extend the landing gear using the emergency gear extension procedures, but the gear down light did not illuminate.
The pilot reported the condition to the tower controller, and made a low approach so that the tower controller could visiually check the position of the landing gear. The controller advised the pilot that the gear appeared to be down. The pilot elected to land.
During the roll out all three landing gears remained extended, but as the airplane slowed, the right main landing gear collapsed. The airplane veered off the runway and into a runway light.
The post-accident examination of the right main landing gear revealed that the truss assembly hook assembly did not travel over the truss pin. The landing gear was tested, and the right main landing gear did not lock on any attempt.
In addition, the right main landing gear truss bracket and stud had excessive friction and prevented the side brace from fully rotating, subsequently preventing the truss hook from traveling over the lock pin. The right main landing gear truss bracket pin had little or no grease present, however, the left main landing gear truss bracket pin had grease indications around the pin and zerk fitting.
A review of the airframe maintenance records indicated that about a month before the accident, the airplane had a 100-hour inspection and a side brace mount assembly was installed in the right main landing gear. The mechanic who performed the maintenance stated that he could not find any guidance in the maintenance manual on how to remove and install the new bushing, therefore, he replaced the bushing and verified that there was movement between the two parts, and then reinstalled the side brace assembly on the airplane. Investigators were able to locate the information in the maintenance manual for the servicing of the landing gear. The accident occurred about 38 hours after the 100-hour inspection.
Probable cause: The mechanic’s improper installation and lubrication of the bushing on the right main landing gear truss assembly, which resulted in the landing gear not locking in the down position.
NTSB Identification: ERA12LA117
This December 2011 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.