ERA26LA009

Maintenance personnel’s improper rigging of the elevator trim system, which resulted in a hard landing. Contributing was the maintenance personnel and pilot’s failure to perform adequate post maintenance/preflight inspections.

The pilot of the skydive airplane reported that after the skydivers left the airplane in flight, he attempted to close the jump door. He was unable to secure the jump door and let go to “reset and make a radio call,” at which time the door began to flap uncontrollably. The pilot grabbed the door and continued to hold it in the closed position. While on final approach to land the pilot, while holding the jump door, attempted to add elevator trim to assist him with the landing flare. After moving the cockpit trim wheel in the nose up direction the nose of the airplane pitched down resulting in a hard landing on the nose landing gear and substantial damage to the fuselage. A Federal Aviation Administration inspector examined the airplane after the accident and found that the elevator trim control was improperly rigged and that when the cockpit trim wheel was turned in the nose up direction, the elevator trim flight control surface moved in the nose down direction and vice versa. A review of maintenance records for the 10 years preceding the accident flight did not show any specific entry for elevator trim tab rigging or maintenance. A review of the checklist used for the airplane’s annual inspection, which had been completed about two months before the accident, indicated that an elevator trim control check was completed. A logbook entry dated about one month before the accident stated the pedestal was removed. During a postaccident interview, the mechanic who performed that work described that he blocked the elevator trim cables (blocking is a term that indicates the control cables were secured to prevent movement of the cables) while the pedestal was removed. The elevator trim chain was then removed from the sprocket to complete the removal of the pedestal, before being reinstalled at the completion of the maintenance task. The mechanic stated he did not recall making a functional control check of this system, post maintenance. Given this information it is likely that the mechanic incorrectly installed the elevator trim control chain at the conclusion of the maintenance he had performed and that his failure to perform a post maintenance flight control check resulted in him not detecting this defect. Additionally, had the pilot completed a thorough preflight inspection of the airplane prior to the accident flight, it is likely that this defect could have been detected and addressed before resulting in the control anomaly that occurred during the accident flight.