What happened
On 08 November 2007, a Beechcraft F33A, registration ZS-JXZ, was conducting a local private flight departing from New Tempe Aerodrome. After approximately one hour of flight time, the pilot attempted to extend the landing gear but found the system failed to deploy, with no green down-and-locked indications visible in the cockpit.
In an attempt to rectify the situation, the pilot reset the landing gear circuit breaker and made several further attempts to extend the gear through the normal system. When these efforts failed, the pilot attempted to use the emergency landing gear hand crank. However, the pilot discovered that the plastic forward spar cover had been installed in a manner that obstructed the crank's operation. Unable to remove the cover in time due to fuel constraints, the pilot was forced to execute a landing at Bloemfontein Aerodrome with the gear retracted. The aircraft sustained a propeller strike and deep scratches to the fuselage underside, but the pilot escaped without injury.
The investigation
An investigation by the SACAA AIID examined the mechanical state of the aircraft and the maintenance history of the components. Post-accident testing of the landing gear on jacks revealed that the primary extension and retraction systems were functioning normally. Subsequent inspections at a maintenance facility led to the replacement of the electrical gear motor as a precaution.
Investigators focused on the installation of the forward carry-through spar cover. The investigation established that the aircraft had recently undergone interior refurbishment and a Mandatory Periodic Inspection (MPI). The investigation found that the emergency hand crank had been positioned behind the spar cover in a way that prevented its use, a condition that should have been identified during the maintenance release process.
Findings
- The primary cause of the inability to use the emergency system was the improper installation of the plastic forward spar cover, which physically blocked the emergency hand crank.
- The maintenance organization failed to verify that the hand crank was correctly positioned and accessible prior to issuing the certificate of release to service during the recent MPI.
- The landing gear system itself was found to be mechanically functional, with the failure to extend being of an undetermined cause.
- The pilot's safety was maintained by the use of a safety harness and the low impact forces of the belly landing.