What happened
On July 28, 2015, a Beechcraft 400A, registration HK4756, was operating a non-scheduled passenger flight from Fort Lauderdale-Hollywood International Airport (KFLL) to El Dorado International Airport (SKBO). The flight was operated by SEARCA S.A.
While descending from FL450 to FL260 within the Bogotá Upper Control Area, the aircraft experienced a dual engine flameout. The loss of power was accompanied by a progressive depressurization of the cabin, necessitating the use of oxygen masks by the two crew members. The loss of engine power also caused a loss of electrical power, forcing the crew to rely on the emergency battery for essential instruments.
Following the failure, the crew performed a controlled descent, maintaining high airspeed to avoid stalling at high altitudes. Despite two unsuccessful attempts to perform an in-flight restart of the number two engine, the crew executed an emergency landing at the Germán Olano Air Base (SKPQ) in Puerto Salgar, Cundinamarca. The aircraft landed without power, and while the landing was without injuries to the two crew members, there was evidence of significant water ingestion in the engines upon arrival.
The investigation
The GRIAA investigation examined the flight history, maintenance records, and environmental conditions. The investigation noted that the aircraft was equipped with Pratt & Whitney JT15D-5 engines and that all regulatory maintenance was up to date. Investigators also reviewed the crew's use of the engine anti-ice system, noting that the crew had used the system for approximately one minute per hour during cruise.
Technical analysis focused on the engine performance during the descent and the presence of convective weather. While the crew reported that visibility was clear and no moisture was visible prior to the descent, the aircraft eventually entered Instrument Meteorological Conditions (IMC) characterized by precipitation and thunderstorms during the emergency descent.
Findings
- The primary cause of the dual engine flameout was engine icing caused by the ingestion of moisture/water during the descent.
- The crew initiated the descent into an area of convective activity where moisture was present, despite the engine anti-ice system having not been used recently.
- The aircraft entered severe weather conditions, including thunderstorms and precipitation, during the emergency descent.
- There was a lack of standardized procedures within the operator's manual regarding the specific timing for activating engine anti-ice systems prior to descent in high-altitude environments.