The following information provides an awareness of problems that might be avoided in the future. The information is based on final reports by official investigative authorities on aircraft accidents and incidents.
Boeing 757-200. Substantial damage. Three minor injuries.
The captain told investigators that she observed a slight yaw as the landing gear was being retracted during departure in visual meteorological conditions (VMC) from Hartsfield–Jackson Atlanta (Georgia, U.S.) International Airport shortly after midnight on June 21, 2011. The 757 was climbing through 3,000 ft a few seconds later when the flight crew received indications of a fire in the no. 1 (left) engine.
The crew shut down the left engine, declared an emergency and turned back to the airport. They subsequently conducted an uneventful, but overweight, single-engine landing on Runway 26L, said the report by the U.S. National Transportation Safety Board (NTSB).
After the 757 was stopped on the runway, aircraft rescue and firefighting personnel extinguished the engine fire. The captain ordered an emergency evacuation through the exits on the right side of the airplane. Three passengers sustained minor injuries while exiting the airplane on slides. The other 169 passengers and the six crewmembers were not hurt.
Damage was limited to the left engine and its mounting pylon and cowlings. “Examination of the engine found extensive fire damage and thermal distress in the fan and core compartments, with the vast majority of the thermal distress and the most extensive fire damage located in the fan compartment between and including the intermediate case and the turbine exhaust case,” the report said.
Further examination of the Pratt & Whitney PW2037 turbofan engine revealed that the fire had started when the fuel flow transmitter’s end housing partially separated from the main housing, creating a 0.3-in (0.8-cm) gap, through which fuel under high pressure escaped from the housing and ignited on contact with the hot engine cases.
The end housing on the fuel flow transmitter (FFT) is attached to the main housing with four through-bolts. The bolts engage threaded inserts in the main housing, which has tapped threads that accommodate the inserts. Investigators found that three of the threaded inserts had been partially pulled out of the main housing, and one had sheared.
“All of the inserts and the bolts were in good condition,” the report said. “However, the main housing tapped threads that accommodate the inserts exhibited sheared and flattened threads at each of the four locations,” the report said.
Investigators found several inconsistencies in the FFT component maintenance manual, including specification of two different torque values for the end housing bolts and inadequate instructions for the application of graphite lubricant to the bolts. Tests showed that the amount of lubricant applied, as well as whether lubricant is intentionally or inadvertently applied to the washers, are significant factors in proper installation of the bolts. Moreover, the manual did not specifically state that used washers must not be used during reassembly of the component.
The report said that, based on the findings of the accident investigation, changes to the FFT maintenance manual were proposed to “ensure a more consistent FFT assembly practice.”
Power Loss Prompts RTO
Airbus A330-243. Substantial damage. No injuries.
The A330 was departing from Manchester (England) Airport with 328 passengers and 11 crewmembers for a scheduled flight to the Dominican Republic the morning of June 24, 2013. The aircraft was accelerating through 105 kt on Runway 23R when it abruptly yawed right. The captain called out “stop” and took control from the copilot. The pilots completed the rejected takeoff (RTO), bringing the aircraft to a stop on the runway.
“Initially, it was unclear what had taken place, but an ECAM [electronic centralized aircraft monitor] warning confirmed that a right engine failure had occurred,” said the report by the U.K. Air Accidents Investigation Branch (AAIB).
Videos showed that the right engine had emitted a flash of flame and a large cloud of smoke. “This was accompanied by a bang, followed by significant shuddering of the engine pylon and nacelle,” the report said.
Examination of the Rolls-Royce Trent 772B-60 engine, which had undergone 5,200 cycles since its last overhaul, revealed that a blade on the high-pressure turbine had fractured just above its root. The blade was carried downstream, causing further release of debris that caused the intermediate- and low-pressure spools to seize.
“The blade failure was caused by high-cycle fatigue crack propagation with crack initiation resulting from ‘Type 2 sulphidation’ corrosion,” the report said, explaining that this type of corrosion occurs when a metal component comes in contact at high temperature with sulfur from fuel or from airborne contaminants, which causes decay of the protective oxide layer and weakening of the component.
Unstable and Unprofessional
Beech 400A. Substantial damage. Two serious injuries, two minor injuries.
Before taking off from Gadsden, Alabama, U.S., for a business flight to Atlanta, Georgia, the morning of June 18, 2012, the pilot calculated a reference landing speed of 120 kt and a landing distance of 3,440 ft (1,049 m) at Dekalb Peachtree Airport. The pilots did not review these calculations after departure, according to the NTSB report.
The copilot, who had 3,500 flight hours, including 150 hours in type, flew most of the flight from the left seat while receiving almost continuous instruction and coaching by the pilot, who had logged 1,500 of his 10,800 flight hours in type.
VMC with light winds prevailed at Dekalb Peachtree, and the flight crew was cleared for a visual approach to Runway 20L, which was 5,001 ft (1,524 m) long. The Beechjet was on a right base leg when the pilot took control from the copilot and began a turn to final approach.
“During the approach, the enhanced ground-proximity warning system (EGPWS) sounded the aural caution ‘sink rate, sink rate’ and also the aural warning ‘pull up, pull up’ several times,” the report said. “The CVR [cockpit voice recorder] did not record comments from either flight crewmember about the cautions or warnings. They performed no maneuvers in response to the cautions or warnings and elected to continue the approach to the runway rather than perform a go-around, which is what they should have done.”
The CVR captured a comment, “way too fast,” by the pilot during final approach. Witnesses told investigators that the Beechjet’s flaps did not appear to be extended. The airplane was 0.5 nm (0.9 km) from the runway and 153 ft above runway threshold elevation when a groundspeed of 194 kt and a descent rate greater than 2,150 fpm were recorded.
The Beechjet touched down with about 2,970 ft (905 m) of runway remaining. The pilots deployed the thrust reversers and speed brakes, and applied maximum wheel braking, but the airplane overran the runway, traveled down an embankment and across a service road, and came to a stop about 800 ft (244 m) from the departure threshold.
The landing gear separated, and the fuselage partially fractured in two places. Both pilots were seriously injured, and their two passengers sustained minor injuries.
NTSB said that the probable cause of the accident was the “flight crew’s failure to obtain the proper airspeed for landing” and that contributing factors were “the failure of either pilot to call for a go-around and the flight crew’s poor crew resource management and lack of professionalism.”
Beech King Air E90. Destroyed. One fatality.
A company in DeKalb, Illinois, U.S., had hired the pilot to transport aircraft parts to Mexico and then deliver the King Air to another operator. The flight to Mexico, planned for July 6, 2012, was delayed for inspection of a recent propeller installation and a return of the airplane to service by the company’s chief mechanic. However, shortly after midnight, the chief mechanic told the pilot that he was too tired to perform the inspection and would complete the work the next morning.
Nevertheless, the pilot departed without authorization from DeKalb at 0230 to position the airplane to Brownsville, Texas, the NTSB report said. It was his first flight in the airplane. The pilot had not obtained a preflight weather briefing or filed a flight plan, but he did request and receive flight-following service from air traffic control (ATC).
The King Air was in cruise flight at 14,500 ft at about 0400 when a Dallas–Fort Worth Center controller told the pilot, “I’m showing some moderate, heavy and extreme precipitation now [at] 12 o’clock and about two miles. It just popped up.”
“Yeah, I’m seeing some weather, sir,” the pilot said. “Do you have a recommendation [for] deviation left or right?”
“No, I really don’t,” the controller replied. “It looks like you are heading right for it. It looks like the heavier stuff, most of it, is to your left, to the east, so maybe going west would be better.”
Accordingly, the pilot advised that he was changing course 25 degrees to the right. “That’s fine,” the controller said. “Whichever way you need to go is fine.” A few minutes later, the controller inquired about the pilot’s ride conditions, but there was no response. Radar contact was lost shortly thereafter.
The wreckage of the King Air later was found in Karnack, Texas. “A review of the radar data, available weather information and airplane wreckage indicated that the airplane flew through a heavy to extreme weather radar echo containing a thunderstorm and subsequently broke up in flight.”
NTSB concluded that the probable cause of the accident was “the pilot’s inadvertent flight into thunderstorm activity” but said that a contributing factor was “the failure of [ATC] personnel to use available radar information to provide the pilot with a timely warning that he was about to encounter extreme precipitation and weather along his route of flight or to provide alternative routing to the pilot.”
Weakened Gear Collapses
ATR 42-320. Substantial damage. Four minor injuries.
VMC with winds from 210 degrees at 16 kt prevailed at Jersey Airport in Britain’s Channel Islands the morning of June 16, 2012, and the flight crew conducted a visual approach to Runway 27. “The commander reported that both the approach and touchdown seemed normal, with the crosswind from the left resulting in the left main gear touching first,” the AAIB report said.
Both pilots heard a noise that they thought was from a tire bursting, and the aircraft rolled left until the wing tip and propeller struck the runway. The aircraft quickly came to a stop to the left of the runway centerline. The commander shut down the engines, and the flight attendant assisted the passengers in evacuating the aircraft. Four of the 40 passengers sustained minor injuries during the evacuation.
Examination of the left main landing gear revealed that the upper arm on the left side brace had fractured. “Evidence provided by the flight data recorders indicates that the landing was not extraordinary and that it was not considered to have been a contributing factor in the collapse of the landing gear leg,” the report said. Investigators found signs that the side brace had been cracked when subjected to overload during a previous flight.
Radio Contact Lost
Mitsubishi MU-2B. No damage. No injuries.
The flight crew was ferrying the MU-2 from the Solomon Islands to Melbourne, Victoria, Australia, with an intermediate stop at Townsville, Queensland, on April 5, 2013. Shortly after departing from Townsville at 1354 local time, the pilots heard static in their headsets and found that they were able to hear radio transmissions from ATC but that their VHF (very high frequency) radios were transmitting only carrier wave (no voice).
The pilots tried unsuccessfully to resolve the problem by turning the two VHF radios on and off, changing frequencies, recycling the circuit breakers, changing headsets and using the handheld microphone, said the report by the Australian Transport Safety Bureau (ATSB).
The pilot later told investigators that they could not return to Townsville because the aircraft exceeded its maximum landing weight. “He also considered changing the transponder to the radio failure code of 7600, however elected to continue with the code previously assigned as the aircraft had already been identified on radar by Townsville ATC,” the report said.
The aircraft remained in ATC radar contact throughout most of the flight but was not in radio contact for 3 hours and 35 minutes. The aircraft was about 230 nm (426 km) north of Melbourne and at 21,000 ft when the crew was able to establish normal radio communications with ATC on a frequency relayed by the crew of another aircraft. The MU-2 subsequently was landed without further incident.
Investigators found that the radio malfunction resulted from water that had leaked onto, and caused corrosion of, two main radio isolator breakers. “The aircraft had been left outside for some time and subjected to tropical storms,” the report noted.
Prop Feathering Delayed
Piper P-Navajo. Substantial damage. One fatality.
The pilot took off from Dalton, Georgia, U.S., the afternoon of June 30, 2012, to have an annual inspection performed in Douglas, Georgia. The NTSB report noted that the inspection was 12 days overdue.
Witnesses about 2 mi (3 km) from the departure runway saw the Pressurized Navajo flying low and descending. One witness said that the left engine appeared to be at full power, and the right engine and propeller were not operating. The airplane pitched up above a power line, rolled right and descended into wooded terrain.
Examination of the wreckage revealed that the propeller had not been feathered promptly after the right engine failed for reasons that could not be determined because of impact and fire damage. The report said that the right engine had accumulated 1,435 hours since it was overhauled 24 years earlier; the recommended time between overhauls of the Lycoming TIGO-541 engine is 1,200 hours or 12 years.
NTSB said that a contributing factor in the accident was the absence of guidance in the pilot’s operating handbook that the propeller should be feathered before rpm decreases below 1,000 rpm after a power loss.
Sick Pilot Loses Control
Beech B95 Travel Air. Substantial damage. Four fatalities.
The pilot landed the Travel Air in Holbrook, Arizona, U.S., for fuel during a flight from California to Texas on June 24, 2009. Witnesses said that the pilot appeared to be ill and that he rested on a sofa while his passengers had lunch.
Shortly after takeoff from Holbrook, the airplane made a 45-degree right turn at about 300 ft and then entered a left turn. The roll steepened past the vertical, and the airplane descended to the ground, killing the four occupants.
“It was very likely that the acute gastrointestinal distress the pilot was suffering at the time impaired his ability to successfully fly the airplane,” the NTSB report said. “Due to his condition, the pilot likely decided to return to the departure airport but failed to maintain control of the airplane.”
Leak Causes Gear to Jam
Piper Chieftain. Substantial damage. No injuries.
After landing at Providenciales, Turks and Caicos Islands, the evening of June 28, 2013, the pilot noticed that the left main landing gear oleo strut was leaking oil. “After consultation with his employer, it was decided to ferry the aircraft back to its base [on Grand Turk] for rectification,” said the AAIB report.
The flight crew was unable to extend the main landing gear on approach to Grand Turk. They conducted a go-around and tried without success to extend the main gear. “The pilot declared an emergency and committed himself to a wheels-up landing,” the report said. “He raised the nose landing gear and feathered both engines on final approach, closing the firewall fuel valves and selecting fuel off. The landing was successful, and there was no fire.”
Examination of the left main gear revealed that the leak originated from a twisted and broken O-ring seal. The leak prevented the oleo strut from extending fully and caused the torque link to foul inside the wheel well.
Fuel Unporting Causes Flameout
Bell 206-L3. Substantial damage. No injuries.
Before departing on a chartered survey flight of the Buccaneer Archipelago in Western Australia the morning of June 8, 2013, the pilot determined from gauge indications that the LongRanger had sufficient fuel for the flight.
“The operator’s fuel management system was almost totally reliant on the fuel quantity indicating system and, as a consequence, lacked a high level of assurance,” the ATSB report said.
The helicopter was at 1,000 ft and heading to Cone Bay for refueling when the engine flamed out. The pilot deployed the floats, but the LongRanger rolled inverted shortly after touching down on the water. The pilot and his four passengers were rescued by a boat crew.
“The ATSB found that, without the pilot realising, the fuel on board was probably sufficiently low to allow momentary unporting of the fuel boost pumps, which interrupted the flow of fuel to the engine,” the report said. “Contributing to the pilot’s lack of awareness of the fuel state was a likely malfunction of the helicopter’s fuel quantity indicating system and a faulty low fuel caution system.”
Tail Rotor Driveshaft Disconnects
Bell 206L-4. Substantial damage. No injuries.
The helicopter departed from Abbeville, Louisiana, U.S., the morning of June 6, 2013, for an apparent fire-fighting mission. It was the LongRanger’s first flight following extensive maintenance that had included removal and installation of the tail rotor gearbox.
After about 40 minutes of flight, the helicopter was approaching a canal at 20 ft to pick up an external load of water when the pilot heard a loud pop. The helicopter began to spin, and the pilot was unable to recover. He reduced power, and the helicopter descended into the canal and settled in about 3 ft (1 m) of water. Damage was substantial, but the pilot and his passenger were not hurt.
Examination of the helicopter revealed that the tail rotor driveshaft had become partially disconnected. “Of the driveshaft’s two bolts, one remained with its associated nut,” the NTSB report said. “However, the other bolt had backed out of the driveshaft but remained in the coupling; its corresponding nut was missing.”
The safety board concluded that the probable cause of the accident was the “failure of maintenance personnel to ensure adequate torque of a tail rotor driveshaft coupling bolt, which resulted in the partial disconnection of the driveshaft.”