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Undetectable subsurface defect led to uncontained engine failure on American Airlines Boeing 767
1 February 2018

Undetectable subsurface defect led to uncontained engine failure on American Airlines Boeing 767

American Airlines flight 383 after evacuation (NTSB)

The NTSB determined that an internal defect in a Boeing 767 engine caused an uncontained engine failure resulting in a fire and the emergency evacuation of all aboard.

American Airlines flight 383, a Boeing 767 bound for Miami, was on its takeoff roll at Chicago O’Hare International Airport Oct. 28, 2016, when a turbine disk in the right engine failed, sending metal fragments through a fuel tank and wing structure. The flight crew rejected the takeoff just as the jetliner approached takeoff speed and stopped the airplane on the runway. All 161 passengers and 9 crewmembers evacuated as emergency responders battled the fuel-fed fire. The airplane was damaged beyond repair. One passenger was seriously injured.

The failed turbine disk was recovered in four pieces, one of which weighed 57 pounds and was found more than a half mile from the airplane. Through extensive examination of the disk fragments at the NTSB lab in Washington investigators determined there was a subsurface defect in the disk at the time of manufacture. Because of the nature of the defect and the limits of inspection methods, the NTSB concluded the defect was likely undetectable when the disk was produced in 1997.
Investigators further determined the defect had been propagating microscopic cracks in the disk for as many as 5,700 flight cycles – one takeoff and one landing – prior to the accident. Although the disk had been inspected in January 2011, the NTSB said the internal cracks were also most likely undetectable at that time because the current required inspection methods are unable to identify all subsurface defects.

The NTSB determined the pilots made the appropriate decision to abort the takeoff and shut down the damaged engine. Because the pilots were working with a checklist that didn’t differentiate between an engine fire in the air from one on the ground, the undamaged engine was not immediately shut down. The passenger who was seriously injured sustained those injuries as a result of evacuating the airplane, as directed by a flight attendant, and encountering jet blast from the engine that was still running.

The NTSB discovered numerous problems with the evacuation, including a lack of communication between the flight deck and cabin crew, deviation by a flight attendant from emergency evacuation procedures, and the crew’s lack of coordination following the evacuation.
The NTSB also noted the flight attendants, who had difficulty using the aircraft interphones to communicate with the cockpit and passengers, were inadequately trained by American Airlines on the different interphone systems installed in its planes.
Video of the evacuation as well as accounts by flight attendants revealed many passengers disregarded pre-flight safety instructions to leave personal belongings behind and instead exited the burning airplane with carry-on luggage.

More information:

 

NTSB details another Airbus A320 losing an improperly closed fan cowl door on departure

The NTSB published an investigation report on another incident involving an Airbus A320 losing an improperly closed fan cowl door on departure.

Parts of the Aruba Airlines A320 fan cowl door (NTSB)

On 19 September 2016, an Aruba Airlines Airbus A320-200, registration P4-AAA, flight AG820, from Miami International Airport (MIA), Florida, USA, to Oranjestad-Queen Beatrix International Airport (AUA), Aruba, powered by two International Aero Engines (IAE) V2527 turbofan engines experienced a separation of the outboard fan cowl from the right-hand engine during takeoff.

The flight crew was unaware of any anomalies until a passenger alerted the cabin crew of what he saw and the cabin crew relayed the message to the flight crew. The flight crew leveled off at FL220 to assess the damage to the airplane. The crew was not sure if the panel had detached completely or was not visible from inside the airplane. All systems appeared normal in the cockpit but as a precaution, the crew elected to return to Miami. The flight had an uneventful landing on runway 09 at Miami Airport about 40 minutes after departure.
There were no injuries. The aircraft sustained damage to the engine, engine pylon, right main landing gear, right main landing gear door and right fuselage.
The night prior to the incident the airplane was in maintenance where mechanics were completing a routine weekly check. Part of the weekly check was to open the fan cowl doors to inspect the Integrated Drive Generator (IDG). Following the maintenance check, the cowl doors were closed and latched.
Because the gate area where the maintenance was being performed was dark, the mechanic who completed the work used a flashlight to verify the latches were flush and made sure he heard a click. A second mechanic who was assisting, also verified that the latches were flush but did not use a flashlight; he stated in a post-incident interview that he could see they were flush. The task was then signed off in the logbook as complete but did not specify that the cowls had been opened and closed. The morning of the incident, about 04:30, the supervisor in charge of maintenance for Aruba Airlines performed a walkaround (although not required) using a flashlight and did not notice anything unusual about the cowl. According to the Aruba Airlines A318/A319/A320/A321 Flight Crew Operating Manual, section “Procedures – Normal – Standard Operating Procedures – Exterior Walkaround,” the fan cowl doors were to be checked that they were “closed/latched.” The first officer conducted an exterior walkaround prior to departure and did not notice any abnormalities. He stated that to check the cowl he bent down and checked that it was flush and latched.

The National Transportation Safety Board in their report determined the probable cause(s) of this incident to be: the incorrect latching of the #2 Engine Fan Cowl following a routine maintenance check that resulted in separation of the cowl during takeoff.

 

This incident is one in over 40 fan cowl loss events involving Airbus A320-family aircraft since 1992. Despite several airworthiness actions over time, incidents involving improperly closed cowl doors going undetected keep recurring.

Selection of incidents and accidents:

 

Report: Russian BAe-125 touches trees after crew sets wrong altimeter pressure (QNH instead of QFE)

Papua New Guinea AIC issued investigation update on fatal BN-2A Islander accident

Photo of the BN-2A wreckage taken using a drone (PNG AIC)

Papua New Guinea Accident Investigation Commission (AIC) issued a preliminary report on their investigation into the December 23, 2017 fatal accident involving a BN-2A Islander.

The BN-2A Islander aircraft, registered P2-ISM, owned and operated by North Coast Aviation, impacted a ridge, at about 9,500 ft on the ridge that runs down towards the Sapmanga Valley from the Sarawaget Ranges, Morobe Province in Papua New Guinea. The pilot elected to track across the Sarawaget ranges, from Derim to Nadzab Airport, not above 10,000 ft. GPS recorded track data immediately prior to the last GPS fix showed that the aircraft was on a shallow descent towards the ridge at that time. The aircraft impacted the ridge about 150 metres beyond the last fix.
During the search for the aircraft, what appeared to be the right aileron was found hanging from a tree near the top of the heavily-timbered, densely-vegetated ridge. The remainder of the wreckage was found about 150 m from the aileron along the projected track. The aircraft impacted the ground in a steep nose-down, right wing-low attitude. The majority of the aircraft wreckage was contained at the ground impact point. The aircraft was destroyed by impact forces. The pilot, the sole occupant, initially survived. The pilot had made contact with one of the operator’s pilots at 16:15 on 23 December.
Bad weather in the area prevented a recovery until December 26. By that time the pilot had died of his injuries.

On 6 January 2018, the AIC investigation team, assisted by two aircraft engineers from North Coast Aviation, reached the accident site and conducted the on-site phase of the investigation.
The investigators used the AIC’s recently acquired drone to survey the accident site, which enabled the investigation team to capture video imagery and photographs from above the trees, and below the foliage canopy over the accident site. Previously a helicopter would have been required, and due to rotor downwash disrupting the wreckage, a helicopter would not be able to gain such close access.

More info:

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ATSB releases preliminary report on hard landing accident of ATR 72-600 at Canberra Airport, Australia

The ATSB released a preliminary report into a hard landing accident involving an ATR 72-600 at Canberra Airport, Australia on 19 November 2017.

The aircraft was being operated by Virgin Australia as flight VA646 on a scheduled passenger flight from Sydney to Canberra. On board the aircraft was the captain, first officer, a check captain, two cabin crew and 67 passengers.
The first officer was pilot flying, and the captain was pilot monitoring. The check captain was positioned in the observer seat on the flight deck and was conducting an annual line check of the captain along with a six month line check of the first officer over four flights on the day. The occurrence flight was the last of these flights.

At about 13:20 local time the flight crew were conducting a visual approach to runway 35 at Canberra. The calculated approach speed was 113 kt. At 13:20:52, nine seconds prior to touch down, the aircraft approached the runway at a height of about 107 ft, slightly above the desired approach path. The flight crew reported that at about this time, there was turbulence and changing wind conditions. Flight data showed that at this time, speed had increased to 127 kt. In response to the increasing speed, the first officer reduced power to near flight idle.
Over the next five seconds, the descent rate increased significantly and the speed reduced.
During the last 50 ft of descent, the captain twice called for an increase in power and then called for a go-around. The first officer responded by increasing the power at about the same time as the aircraft touched down.
At 13:21:01, the aircraft touched down heavily on the main landing gear and rear fuselage with a peak recorded vertical acceleration of 2.97G. Assessing that the aircraft was under control, the captain immediately called to the first officer to cancel the go-around and then took control of the aircraft. The flight crew completed the landing roll and taxied to the gate without further incident.

After shutting down the engines, the flight crew reviewed the recorded landing data which indicated a hard landing had occurred, requiring maintenance inspections. The captain then made an entry in the aircraft technical log, and subsequent inspections revealed that the aircraft had been substantially damaged. There were no reported injuries.

More information:

Report: Distraction, high workload factors in A320 descent below minimum safe altitude at Perth

Report: failure to follow guide line causes Airbus A319 to hit jetway at Ibiza Airport, Spain

Report: Airbus A319 heavy landing after FMGC failure on final approach