Italian investigators have disclosed that there were no engine de-pairing requirement in place for the Rolls-Royce Trent 1000s fitted to a Norwegian Boeing 787 before one of its powerplants failed after take-off from Rome. The engines were subject to a modification – under a service bulletin designated 72-H818 – which introduced an intermediate-pressure turbine blade with a different parent material and coating, to protect against corrosion and fatigue due to sulphidation. A separate service bulletin had set out a de-pairing life to protect against the risk of dual engine failure. Italian investigation authority ANSV says Rolls-Royce used statistical models, based on blade sampling and fleet data analysis, to derive a blade life limit for different groups of serial numbers. This enabled a further bulletin to set a blade hard life which was significantly lower than that at which certain in-service engines – those which had yet to receive the newly-developed blades – would have to be de-paired. As a result, says ANSV, Rolls-Royce agreed with the European Union Aviation Safety Agency to remove the de-pairing requirement. But the failure of the left-hand engine on the Norwegian 787-8, on 10 August, occurred 1,210 cycles after the installation of its intermediate-pressure turbine module – failing 200 cycles before its hard life limit of 1,410 cycles. The aircraft's other engine had performed more cycles – a total of 1,337 – and was even closer, just 103 cycles, to its own limit of 1,440. ANSV says this showed the hard life limit was "not sufficient" to avoid a detrimental effect on safety, and left the aircraft vulnerable to dual engine failure, particularly given that a remaining operative engine "undergoes overall higher solicitations". It has recommended that EASA evaluate de-pairing criteria for engines yet to receive new blades, in order to avoid two such engines being installed on the same aircraft. ANSV acknowledges that Rolls-Royce, on 19 September, revised the service bulletin for managing these engines, reducing the blade life limit for specific engine serial numbers. EASA endorsed this revision through an airworthiness directive on 18 October, which takes effect from 1 November. Norwegian's 787 sustained damage not only to the engine exhaust cone but also the left wing, flap fairing, horizontal stabiliser, fuselage and main landing-gear tyres. Debris shed from the powerplant damaged a total of 28 cars and three building awnings.

Source: FlightGlobal

Investigators have determined that an Air Vanuatu ATR 72-500 crew misdiagnosed an engine failure as an electrical smoke problem and consequently referred to the wrong checklist, unwittingly disengaging systems which were not malfunctioning. This left several crucial systems, including brakes and steering, unavailable to the pilots who were then unable to prevent the ATR veering off the runway at Port Vila and crashing into a pair of parked aircraft. The aircraft, bound for Port Vila from Tanna on 28 July last year, suffered a right-hand engine failure while in cruise.
Papua New Guinea's accident investigation commission says smoke travelled from the engine, through the air-conditioning system, into the cabin, cockpit and avionics bay. This triggered a smoke detector in the avionics and electrical compartment and generated an electrical smoke warning – misleading the crew as to the nature of the problem, and prompting them to follow the 'electrical smoke' emergency checklist. The checklist required de-activation of generators and, as a result, the aircraft's main hydraulic pumps were no longer available. This mean the aircraft's main-gear brakes and nose-wheel steering were rendered inoperative. Investigators state that the crew also shut down the right-hand engine after a low oil-pressure warning. Shutting down the engine meant the rudder's travel limitation unit remained locked in high-speed mode, restricting rudder deflection. The aircraft was flying at 201kt at the time. This limitation unit would normally switch automatically to low-speed mode, offering greater rudder authority, when the aircraft decelerated through 180kt. Engine shutdown inhibited this automatic switching, however, and required the pilots to switch to low-speed mode manually to free the rudder. But the crew did not consult the 'before landing' checklist, which meant the rudder stayed locked and offered significantly limited directional authority when the aircraft landed. As the ATR touched down and rolled out, both engine power levers were set to maximum reverse-thrust. With only the left-hand engine operating this generated asymmetric thrust, and the aircraft veered to the left of runway 29. "Use of reverse thrust under the prevailing circumstances was inappropriate," the commission says. The crew was unable to use either the brakes or the nose-wheel steering – owing to the loss of the hydraulic pumps – or the locked rudder to correct the deviation or slow the aircraft. Although the emergency brake was available, the pilots failed to use it. After veering off the runway the aircraft rolled across a taxiway and slowed to around 45kt before colliding with two parked Britten-Norman BN-2 Islanders, substantially damaging both. The inquiry stresses that the engine failure did not cause the landing accident, and pilots are normally trained to land aircraft with an engine inoperative. "Apart from the engine, none of the aircraft systems, including electrical and hydraulic systems, malfunctioned in-flight," it states. "The loss and unavailability of these systems, was induced by flight crew action." Although the ATR sustained serious damage, none of the 39 passengers and four crew members was injured.

Source: FlightGlobal

The head of the Federal Aviation Administration is giving no clue about when his agency might clear Boeing's 737 Max to fly. But when addressing attendees at the ALTA Airline Leaders Forum on 28 October, FAA administrator Stephen Dickson stressed repeatedly that his agency will not clear the aircraft to fly until Boeing fully addresses all the FAA's safety concerns. "The FAA's return-to-service decision will be based solely on our assessment of the sufficiency of Boeing's proposed software update and training" recommendations, Dickson told a packed crowd of ALTA attendees. He insists that the FAA will cut no corners and is completing a new safety review – a message coming amid global concern about seeming lapses in the FAA's original certification of the Max. That concern has led some regulators outside the USA to reconsider the traditional certification approach under which they essentially rubber-stamp the FAA's aircraft type certificates. The European Union Aviation Safety Agency, for instance, has committed to conducting an independent Max review. The aircraft has been grounded globally since March following the October 2018 crash of a Lion Air Max 8 and the March crash of an Ethiopian Airlines aircraft of the same model. Lion Air investigators have pinned that accident on Boeing's flight control system, shortcomings in the FAA's certification and lapses by Lion Air, among other factors. "Other civil regulators have to take their own actions to return the 737 Max to service." Dickson says. "The civil aviation authorities must know we are not resting on the previous safety analysis." Latin American carriers have acquired or ordered nearly 300 737 Max jets, Cirium fleets data shows. Boeing last week said it anticipates regulators will approve the Max's certification before year-end, though the FAA has disclosed no timeline. Dickson concedes the FAA must improve its industry oversight and suggests his agency will adopt some of the various certification improvement recommendations issued by various groups in recent weeks. Recommendations have come from the National Transportation Safety Board, Indonesian accident investigators and an FAA-convened safety panel composed of aviation safety experts from numerous countries. "The FAA is fully committed to address all the recommendations, with special emphasis on those that pertain to returning the 737 Max to service," Dickson says. "What we have done in the past and what we are doing today will not be good enough for the future."

Source: FlightGlobal