Engine failure on microlight following exhaust component separation

Casualties unknown • Grenchen Flugplatz (LSZG), RPAS (Remote Piloted Aircraft Systems), SO, CH

A Windlass Aquilla trike experienced engine failure and fuel starvation during a climb at Ballito Microlight Airfield due to a mechanical failure in the exhaust system.

What happened

On the morning of 24 November 2024, a pilot was operating a Windlass Aquilla weight-shift controlled trike, registration ZU-BUI, on a private flight departing from Ballito Microlight Airfield in KwaZulu-Natal. The flight was intended to be a local circuit under visual meteorological conditions.

After taking off from Runway 18 and reaching an altitude of approximately 850 feet, the pilot initiated a left turn. During this maneuver, the aircraft began experiencing intense engine vibrations. This vibration was so severe that the carburettors were dislodged from the fuel intake, leading to immediate fuel starvation and engine stoppage. The pilot was able to glide the aircraft back to the same runway, performing a successful forced landing. There were no injuries and no damage to the aircraft.

The investigation

An investigation into the mechanical failure focused on the engine's exhaust system. A post-incident inspection by the pilot and a subsequent assessment by a Rotax-approved engineer revealed that a portion of the exhaust outlet pipe had broken off during flight. The missing component was not recovered.

Technical examination of the remaining exhaust hardware showed that the break occurred at a welded joint. The investigation established that the failure was an isolated incident, as no similar failures had been previously recorded in the Rotax exhaust systems examined.

Probable cause

The engine failure was caused by the separation of an exhaust pipe end due to fatigue at a poorly welded joint, which led to propeller impact and the subsequent dislodging of the carburettors.

Frequently asked questions

What happened in the 2018-10-04 SOCIETE DE CONSTRUCTION DAVIONS DE TOURISME DE DAFFAIRES TB 10 accident near Grenchen Flugplatz (LSZG), RPAS (Remote Piloted Aircraft Systems), SO, CH?

A Windlass Aquilla trike experienced engine failure and fuel starvation during a climb at Ballito Microlight Airfield due to a mechanical failure in the exhaust system.

What aircraft was involved and where did it happen?

The accident on 2018-10-04 involved a SOCIETE DE CONSTRUCTION DAVIONS DE TOURISME DE DAFFAIRES TB 10, registration HB-KAU, at Grenchen Flugplatz (LSZG), RPAS (Remote Piloted Aircraft Systems), SO, CH.

What was the probable cause of the accident?

The engine failure was caused by the separation of an exhaust pipe end due to fatigue at a poorly welded joint, which led to propeller impact and the subsequent dislodging of the carburettors.

Investigation report by the Swiss Transportation Safety Investigation Board (STSB / SUST). Original record: https://www.sust.admin.ch/inhalte/AV-berichte/HB-KAU.pdf. This page is a structured re-presentation; facts and quotes are in the Swiss Transportation Safety Investigation Board (STSB), Switzerland.

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