What happened
On 30 October 2012, a Titan T-51 Mustang, registration G-MUZY, was conducting a private local flight when the pilot encountered significant mechanical failures during the landing circuit at Wellesbourne Mountford Airfield. While approaching Runway 18, the pilot attempted to reduce power but discovered the throttle had jammed in the fully open position. During efforts to clear the jam, the throttle lever suddenly released, only to become stuck in the idle setting.
As the aircraft approached two miles from the runway, the pilot found the landing gear would not extend. Air Traffic Control notified the pilot that the gear was visibly not down. To manage the descent and reduce drag, the pilot raised the flaps and landing gear, ultimately deciding to perform a wheels-up landing on the grass adjacent to the runway. The landing resulted in no injuries to the crew or passenger, though the aircraft sustained damage to the propeller and the underside of the fuselage.
The investigation
Investigators examined the engine compartment and identified that a weld on an exhaust pipe, located under the engine cowling, had fractured. This failure allowed hot gases to escape into the engine bay. The resulting heat caused significant damage to various components, specifically causing the throttle cable to deteriorate and the battery to partially melt.
The failure of the electro-hydraulic landing gear system was attributed to the damage sustained by the battery. While the aircraft was equipped with a standby free-fall extension system, the pilot did not attempt to use this feature during the emergency.
Findings
- A fracture in the exhaust pipe weld released high-temperature gases into the engine compartment.
- Heat-induced deterioration of the throttle cable caused the throttle to jam in the idle position.
- Damage to the battery caused the failure of the electro-hydraulic landing gear system.
- The failure of the exhaust weld likely occurred due to a period of undetected crack development.