Bogotá Capital District

The investigation determined that the accident was caused by the following probable causes:
- Emergency landing of the aircraft on an unprepared field, as a result of a decrease in power, generated by engine failure.
- An engine failure caused by the fracture of three (3) blades of the rotor disk of the high pressure compressor, which caused severe backwards damage to the hot and power section.
Contributing Factors:
- Non-compliance in the engine maintenance process, of what was ordered in AD. No. 2014-17-08R1 FAA (year 2014), which establishes the replacement of the engine blades high pressure compressor in anticipation of material failures in these components.
- Deficient maintenance processes by the provider of this service to the aircraft HK4669G, by not detecting the condition of the high-pressure rotor blades in the boroscopic inspections of the high pressure during routine boroscopic inspections.
- Deficient verification of the Operator's contracted maintenance processes, by not verifying the quality and compliance the quality and full compliance of these processes by the maintenance service provider.

The investigation determined that the accident was caused by the following probable cause(s):
- Loss of in-flight control as a result of slowing below Minimum Control Speed and drag, generated by the failure of the right engine (No. 2).
- Failure of engine No. 2, due to lack of lubrication, possibly caused by oil leakage through an 11.5 mm fracture, found in one of the sides of cylinder No. 2 at the height of the intake valves.
- Inappropriate application by the crew of the emergency procedure for landing with an inoperative engine, by not declaring the emergency, not feathering the propeller of the inoperative engine and configuring the aircraft early for landing (with landing gear and flaps) without having a safe runway, making it difficult to control the aircraft and placing it in a condition of loss of lift and control.

Contributing Factors:
- Failure of the operator to emphasize in the crew training program the techniques and procedures to be followed in the event of engine failure, among others, the declaration of emergency to ATC, the flagging of the propeller of the inoperative engine, the care in the application of power to the good engine so as not to increase yaw and not to configure the aircraft until landing has been assured.
- Lack of emergency calls by the crew, which denotes deficiencies in the Operator's Safety Management System, and which prevented the early warning of the aerodrome support services and deprived the crew of possible assistance from other aircraft or from the same operator.

The pilot lost control of the airplane following a loss of power on the left engine during initial climb. Investigations were unable to determine the exact cause of this loss of power. The aircraft's speed dropped to 107 knots and the pilot likely did not have time to identify the problem. Operation from a high density altitude airport contributed to the accident.

Failure of the right engine during initial climb due to the failure of internal components. The high density altitude was considered as a contributing factor as its affected the aircraft performances.

The inability of the accident aircraft to maintain flight after the loss of power of two engines.
The following contributing factors were identified:
A non-recoverable surge on the engine n°4 during the rotation, resulting in a loss of engine power. Contributing to the surge were the combined effects of the inefficient high pressure turbine, excessive blade-tip clearance, reduced cord of the fan blades and of the leading edges and the effects of high altitude. An undetermined anomaly in the engine n°1, which manifested itself during the extra power, resulted in loss of engine power. Contributing to the loss of engine power was inadequate n°1 operation to maintain the proper speed during the ascent of the aircraft, resulting in extra power use and, in turn, exposing the anomaly of the engine.

Carrying out a landing with an unresolved issue on the left engine, causing the aircraft to be unable to stop within the remaining distance available. The failure to correct the maintenance reports in a satisfactory manner and the failure to properly follow-up on repetitive entries were considered as contributing factors.

The exact cause of the accident could not be determined.

Failure of the right main gear during taxi due to the presence of corrosion in the trunnion.