What happened
On 26 February 2017, a Cessna 152, registration B-HHN, operated by the Hong Kong Aviation Club, departed Shek Kong Airfield for an aircraft rating flight test. The crew consisted of an examiner acting as the pilot in command and a student pilot.
During the flight test maneuvers near the Tap Mun area, the crew noticed abnormal engine noise and vibrations. Although the engine performance briefly appeared to stabilize, the vibration returned shortly after. The pilot in command took control of the aircraft and attempted to return to Shek Kong Airfield. During the attempt to climb, the engine performance deteriorated further, running rough even after power was reduced.
With the engine failing, the pilot in command initiated a forced landing near the Garden Farm Golf Centre in Sam Pui Chau. The aircraft struck trees and vegetation adjacent to the driving range, resulting in major damage to the aircraft. Both crew members escaped the crash without injuries.
The investigation
The AAIA examined the engine's performance and the environmental conditions at the time of the accident. The investigation focused on the engine's vulnerability to icing and the crew's actions during the flight maneuvers. Investigators reviewed the maintenance history, fuel samples, and the pilot's application of carburetor heat during the flight. The investigation also looked into the safety management systems and training procedures utilized by the operator.
Findings
- The engine was susceptible to significant carburetor icing under the prevailing ambient conditions, regardless of the power setting.
- The engine malfunction was likely caused by carburetor icing, which occurred because the carburetor heat was not applied during an unusual attitude recovery maneuver.
- The aircraft's engine performance became unstable during the attempt to climb back to the airfield.