REPUBLIC OF KENYA MINISTRY OF TRANSPORT AND INFRASTRUCTURE AIR ACCIDENT INVESTIGATION

Transcription

1 REPUBLIC OF KENYA MINISTRY OF TRANSPORT AND INFRASTRUCTURE Telegrams: TRANSCOMS. Nairobi Telephone: (020) Website: TRANSCOM BUILDING NGONG ROAD P.O. Box NAIROBI AIR ACCIDENT INVESTIGATION FACTUAL INCIDENT REPORT GMKJA

2 CIVIL AIRCRAFT FACTUAL INCIDENT REPORT CAV/INC/GMKJA/10 OPERATOR: MK AIRLINES LIMITED OWNER: MK AIRLINES LIMITED AIRCRAFT: BOEING REGISTRATION: GMKJA PLACE: HKJK (JKIA) DATE: 10 APRIL 2010 TIME: 1050 hours All times given in this report are Coordinated Universal Time (UTC) East African Local Time is UTC plus 3 hours.

3 TABLE OF CONTENTS ABBREVIATIONS... 5 SYNOPSIS FACTUAL INFORMATION History of Flight Injuries to persons Damage to Aircraft Other damage Personnel Information Captain First Officer Flight Engineer Aircraft Information Meteorological Information Aerodrome Information Flight Recorders Wreckage and Impact Information Medical and Pathological Information Fire Survival Aspects Tests and Research Additional Information Compressor Surge Non-recoverable surge... 14

4 1.16. Useful and Effective Investigative Techniques ANALYSIS CONCLUSIONS SAFETY RECOMMENDATION APPENDICES Appendix I HKJK Aerodrome Chart Appendix IV Aircraft Photographs... 16

5 ABBREVIATIONS AAID - Air Accident Investigation Department AMSL - Above Mean Sea Level ATC - Air Traffic Control EGT - Exhaust Gas Temperature FOD - Foreign Object Damage HKJK - ICAO Aerodrome Designation for JKIA ICAO - International Civil Aviation Organization JKIA - Jomo Kenyatta International Airport KCAA - Kenya Civil Aviation Authority RPM - Revolutions Per Minute SOPs - Standard Operating Procedures FDR - Flight Data Recorder UK AAIB - United Kingdom Air Accident Investigation Branch UKCAA - United Kingdom Civil Aviation Authority

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7 SYNOPSIS The Air Accident Investigation Department (AAID) was notified of an incident by Jomo Kenyatta International Airport (JKIA) Air Traffic Control (ATC) Tower at 1100 hours on 10 April The incident occurred on runway 06 of the airport. An Investigation Team comprising officers from AAID responded to the incident almost immediately on the same day. At 1050 hours on 10 April 2010, a Boeing aircraft of registration GMKJA operated by MK Airlines Limited under Flight Number BGB 118 aborted take-off on runway 06 of JKIA after the crew reportedly heard a loud bang and noticed a drop in the engine 2 RPM to zero. The aircraft was safely taxied off runway 06 with assistance from ATC. There were five (5) crew members on board the aircraft at the time of incident. There were no reported injuries to the crew. The damage to the aircraft was limited to the internal section of engine 2. There was evidence of massive disintegration and rapture of the turbine blades in the final stages of the turbine section. There was no evidence of FOD and the loud bang was probably as a result of a compressor surge on engine 2 during a high power take-off. The investigation did not establish the actual cause of the compressor surge or the cause of disintegration of the turbine blades. The matter was referred to KCAA and the UK AAIB was notified accordingly.

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9 1. FACTUAL INFORMATION 1.1. History of Flight The aircraft Boeing of registration GMKJA was being operated by MK Airlines Limited at the time of incident. On 10 April 2010, the aircraft was performing a scheduled cargo flight from Nairobi JKIA (HKJK) to Manston International Airport (MSE) in the United Kingdom. The flight crew reported that the aircraft had been loaded with 80 tonnes of agricultural produce under the supervision of the loadmaster. At approximately 1000 hours, the crew reported starting normal aircraft preparations for the flight. They conducted preflight checks in accordance with the relevant checklists and the aircraft was reported to be in a satisfactory condition for the flight. There were a total of five persons on board the aircraft including the Captain, First Officer, Flight Engineer, Loadmaster, and Ground Engineer. At approximately 1040 hours the incident aircraft was cleared by ATC to taxi to the holding area of runway 06. Upon receiving takeoff clearance from the ATC, the Flight Crew initiated a high thrust takeoff on runway 06. At approximately 1050 hours when the aircraft was rolling at a speed of about 80 knots, the crew reported hearing a loud bang and they decided to abort the takeoff. They reported the mishap to the ATC. Just before exiting runway 06, the crew noticed that the engine 2 RPM had dropped to zero and there was an exceedance on the engine 2 EGT. The crew reported that they then followed their engine failure checklist and taxied the aircraft off runway 06 with assistance of ATC.

10 1.2. Injuries to persons Injuries Crew Passengers Others Fatal Serious None Damage to Aircraft The damage sustained by the aircraft was limited to the internal section of engine 2. The engine sustained severe visible damage to the turbine section. The final stage turbine rotor blades sheared off at the root and debris of disintegrated blades were scattered on the runway. There were no visible signs of Foreign Object Damage (FOD) on the engine inlet and the aircraft exterior. None 1.4. Other damage 1.5. Personnel Information Captain The captain held a valid Airline Transport Pilot License (ATPL License No. UK/AT/440618D/A) issued by the UK Civil Aviation Authority. The License was valid until 03 April 2012 and the medical certificate issued to the pilot was valid until 14 December The ATPL included a type rating endorsement for B First Officer The First Officer held a valid Airline Transport Pilot License (ATPL License No. UK/AT/443973B/A) issued by the UK Civil Aviation Authority. The License was valid until 20 February 2012 and the medical certificate issued to the pilot was valid until 20 December The ATPL included a type rating endorsement for B

11 Flight Engineer The Flight Engineer held a valid license (License No.UK/FE/200570L/FE) issued by the UK Civil Aviation Authority. The license was valid until 07 September The medical certificate issued to the Flight Engineer was valid 11 February Aircraft Information Manufacturer The Boeing Company Type Boeing Number and type of engines Certificate of Registration Category 4 Pratt & Whitney JT9D GMKJA, UK registered Commercial Air Transport (Cargo) 1.7. Meteorological Information The 1100Z METAR for HKJK indicated that wind was from the East at 3 knots, visibility was better than 10 km, clouds were scattered, the temperature was 26 C, dew point was 13 C, humidity was 44% and QNH was 1019hPa.

12 Time (Z) Temp. Dew Point Humidity QNH Visibility Wind Dir Wind Speed Precip Conditions C 13.0 C 44% 1019 hpa 10.0 km East 3 Knots N/A Scattered Clouds 1.8. Aerodrome Information JKIA (ICAO designation HKJK) is an international airport located eighteen kilometers South East of Nairobi. It is located at latitude S and longitude E at an elevation of 5330 feet AMSL. The aerodrome operates on a 24-hour basis. It has two asphalt runways 06/24 of dimension M. The airport is equipped with air traffic control facilities, radio navigation aids, landing aids and approach, threshold and runway lighting Flight Recorders The aircraft flight recorders were not retrieved for purposes of the investigation Wreckage and Impact Information The aircraft structure remained intact after the incident except for the disintegration of engine 2 turbine blades. The debris of turbine blades was strewn along runway 06. There was no evidence of foreign object ingestion or damage on the engine inlet and aircraft exterior Medical and Pathological Information No medical examination of the crew was conducted Fire There was no evidence of fire resulting from the incident Survival Aspects Not applicable Tests and Research None was conducted

13 1.15. Additional Information Compressor Surge The information on this section is based on various publications by the aircraft manufacturer, aircraft engine manufacturer and the state of design and manufacture. A surge from a turbofan engine is the result of instability of the engine's operating cycle. The actual cause of a compressor surge is often complex. It may be caused by engine deterioration, ingestion of foreign objects (birds or ice), or it may be the final sound from a "severe engine damage" type of failure. The operating cycle of the turbine engine consists of intake, compression, ignition, and exhaust, which occur simultaneously in different places in the engine. The part of the cycle susceptible to instability is the compression phase. In a turbine engine, compression is accomplished aerodynamically as the air passes through the stages of the compressor. The air flowing over the compressor airfoils can stall just as the air over the wing of an aeroplane can. When this airfoil stall occurs, the passage of air through the compressor becomes unstable and the compressor can no longer compress the incoming air. The high-pressure air behind the stall further back in the engine escapes forward through the compressor and out through the inlet. This escape is sudden, rapid and often quite audible as a loud bang similar to an explosion. Engine surge can be accompanied by visible flames forward out the inlet and rearward out the tailpipe. Instruments may show high EGT and EPR or rotor speed changes, but, in many stalls, the event is over so quickly that the instruments do not have time to respond. In modern turbofan engines, compressor surge is a rare event. If a compressor surge occurs during high power at takeoff, the flight crew will hear a very loud bang, which will be accompanied by yaw and vibration. The bang will likely be far beyond any engine noise, or other sound, the crew may have previously experienced in service. The actual cause of the loud bang should make no difference to the flight crew's first response, which should be to maintain control of the airplane and, in particular, continue the takeoff if the event occurs after V1. If the compressor surge occurs below V1, the desired immediate crew response should be a rejected takeoff. Rarely does a single compressor surge cause severe engine damage, but sustained surging will eventually over-heat the turbine, as too much fuel is being provided for the volume of air that is reaching the combustor. Compressor blades may also be damaged and fail as a result of repeated violent surges; this will rapidly result in an engine which cannot run at any power setting.

14 Depending on the reason for the cause of the compressor instability, an engine might experience a single self-recovering surge, multiple surges prior to selfrecovery, multiple surges requiring pilot action in order to recover or a nonrecoverable surge. Non-recoverable surge When a compressor surge is not recoverable, there will be a single bang and the engine will decelerate to zero power as if the fuel had been chopped. This type of compressor surge can accompany a severe engine damage malfunction. It can also occur without any engine damage at all. EPR can drop at a rate of.34/sec and EGT rise at a rate of 15 degrees C/sec, continuing for 8 seconds (peaking) after the thrust lever is pulled back to idle. N1 and N2 should decay at a rate consistent with shutting off the fuel, with fuel flow dropping to 25% of its pre-surge value in 2 seconds, tapering to 10% over the next 6 seconds Useful and Effective Investigative Techniques None 2. ANALYSIS The circumstances of this incident were consistent with a rejected takeoff following a compressor surge during a high power takeoff. The loud bang reported by the flight crew and the subsequent drop in engine 2 RPM and rise in engine 2 EGT was characteristic of a compressor surge on engine 2. According to the pilot report, the engine 2 RPM dropped to zero and an EGT exceedance was also noted on the same engine. The evidence of disintegrated turbine blades found scattered on runway 06 and on engine 2 tailpipe was an indication of severe internal engine damage. The investigation did not establish any evidence of foreign object damage on the engine inlet or aircraft exterior which may have caused the compressor surge and subsequent damage to the engine. The engine damage and fluctuations in RPM and EGT parameters on engine 2 was, therefore, considered to be consistent with a non-recoverable surge during a high power takeoff. The investigation considered that the JT9D turbofan engine was designed to withstand surge at takeoff power, without structural failure, significant overtemperature, or damage significant enough to preclude recovery of engine power, or damage that will lead to subsequent failure. In the case of this incident,

15 the engine did not withstand the surge leading to internal structural failure and EGT exceedance. The EGT exceedance condition was likely because the airflow downstream of the combustion chamber was not sufficient to ensure the cooling of the turbine section. This exceedance was also considered a symptom of the severe engine failure. The investigation did not establish the actual cause of the structural failure of the turbine blades. No detailed internal examination of the engine was conducted to establish the cause of the massive disintegration of the turbine blades. But based on service experience reports, and ruling out ingestion of foreign object as a cause, the internal engine structural failure was likely as a result of: engine deterioration (compressor blade rapture or high wear); bleed system malfunction; malfunction of engine controls (fuel scheduling or surge protection devices). Based on interview information and pilot reports, the crew actions during this incident were considered to be consistent with Standard Operating Procedures (SOPs). According to the pilots, the aircraft preflight checks and engine ground runs prior to takeoff indicated that the aircraft was fit for flight. The flight crew heard a loud bang while on takeoff roll at a speed of approximately 80 knots and made a decision to abort the takeoff. They immediately reported the occurrence to ATC. The rejected takeoff was performed at a speed below V1, which was in accordance with SOPs. The flight crew then carried out an engine shutdown procedure in line with an engine failure checklist. The aircraft was safely taxied off the runway with assistance from the ATC. 3. CONCLUSIONS 1. The Captain and First Officer held appropriate qualifications and experience to fly the Boeing aircraft. 2. The Flight Crews were conducting high-power takeoff on runway 06 of JKIA. 3. The Flight Crews performed a rejected takeoff below V1 on the runway following a loud bang. 4. The loud bang was established to be from engine 2 based on the drop in RPM to zero and exceedance of EGT on the engine. 5. There was no evidence of foreign object ingestion on engine 2 and no evidence of a bird strike on the aircraft exterior.

16 6. Engine 2 sustained massive disintegration of turbine blades. Turbineblade debris that had broken off from engine 2 was found on the runway and on the engine tailpipe. 7. The circumstances of this incident were consistent with a compressor surge on engine 2 during a high power takeoff. 8. The investigation did not establish the cause of the uncontained internal structural failure of engine SAFETY RECOMMENDATION UKCAA needs to consider reviewing the engine condition monitoring programs of MK Airlines to ensure that they meet the relevant requirements and can reliably determine engine deterioration. APPENDICES Appendix I HKJK Aerodrome Chart Appendix IV Aircraft Photographs

17 HKJK Aerodrome Chart

18 Aircraft Photographs

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