Dutch Scientists Suggest Modifying the Boeing 747 Engines After a Failure from goldenfalcon's blog

In its last accident report on a modified Boeing 747-400 freighter (B747-400BCF) that faced a confined engine failure and engine pieces that fell on a Dutch village, the Onderzoeksraad voor Veiligheid (Dutch Safety Board, OVV) made some proposals. 

This incident happened on February 20, 2021, when a Boeing 747-400BCF bearing the registration number VQ-BWT faced a confined engine failure shortly after taking off towards New York's JFK (John F. Kennedy) International Airport from MST (Maastricht) Aachen Airport. Engine 1, the outer wing left-side engine of the aircraft made of the best aircraft parts, had sustained damage. It was run by Longtail Aviation. 

Two people on the ground were injured, but no crew members aboard the 747 were affected. In the town of Meerssen, which is located about two kilometers south of runway 21 at MST, additional damage to vehicles and buildings was noted. The plane made a detour to Liege Airport (LGG) in Belgium after the contained engine failure, where the Boeing 747-400F landed safely. Four turbofan engines from the Pratt & Whitney PW4000 family, which went into operation in January 1993, have completed 9,964 flight cycles and 73,995 flight hours to power the freighter. At the time of the event, the 4 turbofans had 1,998 FCs and 11,516 FHs since their last refurbishment in 2010. 

Boeing 747-400BCF’s Contained Engine Failure

The aircraft made of the best aviation parts was shown to be in normal operating condition in the final report, except for the APU (auxiliary power unit) being unusable because the inlet door was stuck in a half-open position, forcing the crew to account for the extra drag during the takeoff performance calculation. The MEL (Minimal Equipment List) of the operator permitted the operation of the Boeing 747-400BCF in that context. The flight crew began the engines as the aircraft started to taxi to runway 21, as the OVV commented in its last report, and all engine indications were normal. The start-up times were within acceptable ranges. 

The takeoff roll was routine, but at a height of 350 meters (1,150 feet) above mean sea level, the 747 started to roll and yaw to the left when the pilots heard a pounding noise. Also, engine No. 1's exhaust gas temperature surpassed the maximum level, which led to the failure of the power plant and subsequent loss of thrust. There was high damage to the high-pressure and low-pressure turbines of the P&W PW4000. 

Think About Whether SB Should Be a Required AD

Three recommendations were made to different parties by the Dutch investigators. The OVV advised Longtail Aviation to "maintain complete and accessible record maintenance of the (non-)implementation of service bulletins for leased engines of your fleet of commercial air transport airplanes." Second, the FAA was guided by the Dutch investigators to reevaluate whether SB 72-462 should be declared a demand through an AD. 

The institution suggested that the Dutch Minister of Infrastructure and Water Management conduct and publish a study of the dangers of pieces of aircraft disengaging, for example, disengaging engine debris, for living areas near Maastricht Aachen Airport. The investigation stated that although the failure posed no threat to the aircraft's safe operation, the engine parts that were released made a risk to property and people on the ground. 

The engine failure demonstrated the chance of engine pieces flying off and injuring people or causing property damage. Residents near airports are at least subject to two different kinds of risks: first, components coming off the airplane, and second, an aircraft accident. 

No research had been done to evaluate the two threats in the residential areas around MST at the time of the report. An educated choice about the acceptability of these local hazards should be made in light of the findings of such an assessment. The departing engine debris that fell in a village and may have gravely hurt persons in addition to the already existing injuries led the OVV to classify the incident as a serious incident owing to the possibility of an accident.