This June 2009 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.
Aircraft: Cessna 140. Injuries: None. Location: St. Louis. Aircraft damage: Substantial.
What reportedly happened: The accident occurred during the second flight after the airplane had undergone maintenance on the left flap assembly. Shortly after takeoff, the pilot heard a loud bang, followed by repeated banging from behind his position. He performed an immediate landing, touching down on the last 50 feet of runway. There was not sufficient runway to bring the plane to a stop and it went off the runway and nosed over in a wheat field.
The post-accident inspection revealed that the upper half of the left inboard wing fairing was bent upward and aft. The one-piece fairing was properly secured to the lower wing structure, but none of the five upper screws were in place or found on the runway. The fairing upper screw holes did not exhibit any damage. The fairing had been removed during the recent flap maintenance. According to the mechanic who performed the maintenance, the fairing was reinstalled in the presence of several individuals, including the pilot, and that all of the screws were installed before he returned the airplane to service. According to the pilot, during his preflight inspection he visually confirmed that the screws were installed, although he did not verify their security. The lack of damage was not consistent with a progressive loss of the upper screws during flight.
Probable cause: The improper installation of the wing fairing during recent maintenance, which resulted in the partial separation of the fairing shortly after takeoff.
For more information: NTSB.gov. NTSB identification: CEN09LA335