Accident Overview
On Tuesday, 30 April 2024, at 1625Z, a Piper PA-34-200T Seneca, registration ZS-MGW, was on a private flight from Kruger Mpumalanga International Airport (FAKN) to Wonderboom Airport (FAWB) in Gauteng Province, South Africa. The flight was conducted under visual meteorological conditions by day, in accordance with Part 91 of the Civil Aviation Regulations. The aircraft carried one pilot and one passenger; no injuries were reported, but the aircraft sustained substantial damage.
Sequence of Events
The pilot reported an uneventful flight from FAKN. Upon arrival at FAWB, she performed several touch-and-go circuits on Runway 11. During the climb after the first touch-and-go, while completing after-takeoff checks, she noticed the landing gear did not retract. She flew a right-side circuit to troubleshoot but was unsuccessful. When she selected the gear up, a gear unsafe light illuminated. Checking engine cowling mirrors, she saw the nosewheel remained extended. Selecting gear down produced no audible or tactile movement. She maintained circuit altitude and attempted fault-finding by cycling circuit breakers and replacing the left main gear light bulb, all without success. Another pilot at the holding point, listening to her radio broadcast to air traffic control, reported that the landing gear appeared down but could not confirm locking. The pilot then decided on a precautionary landing. She lowered the landing gear and pulled the emergency gear extension handle to release hydraulic pressure and allow gravity extension. Per the Pilot's Operating Handbook, the emergency extension handle must remain in the fully extended position after activation to prevent reapplication of hydraulic pressure. However, during the landing rollout, the landing gear collapsed, and the aircraft skidded on its belly before stopping on Runway 11.
Post-Accident Inspection
A post-accident inspection by an aircraft maintenance organisation (AMO) revealed that the emergency gear lever had been activated but then reset (pushed back) before the gear was down and locked, contrary to the prescribed procedure. The AMO also found that the undercarriage electric motor had failed due to excessive brush wear, caused by hydraulic oil leaking from the pump into the motor. This oil softened the brushes, preventing proper contact with the armature and stopping the motor. The AMO noted that brush wear can be accelerated by hydraulic fluid contamination and considered this wear-and-tear accelerated by the leak.
Findings
- The pilot held a valid Commercial Pilot Licence with a Class 1 medical certificate and had 1,591.1 total flight hours, including 38.8 hours on the accident aircraft type.
- The aircraft had a valid Certificate of Airworthiness and Certificate of Release to Service; it was airworthy at dispatch.
- The 100-hour brush inspection on the landing gear motor had been conducted on 14 February 2023, with the next inspection due at 63 hours.
- The undercarriage lock mechanism operated as expected when tested on jacks, with damage observed on nosewheel doors.
- The electric motor failed due to hydraulic oil leakage into the motor, causing brush softening and loss of contact.
- The pilot did not follow the emergency landing gear extension procedure correctly: the emergency lever was not left in the extended position as required by the POH.
Probable Cause
The hydraulic motor failed during normal landing gear extension, and the pilot did not pull the emergency extension to maximum; this caused the landing gears to collapse.
Contributing Factor
The emergency lever was activated and then reset (or pushed back) before the gear was down and locked. Pushing the lever back after being extended is an incorrect procedure.