Relaxed inspections may have contributed to engine coming off UPS MD-11

Relaxed inspections may have contributed to engine coming off UPS MD-11

A UPS MD-11 crash at Louisville’s Muhammad Ali International Airport last year killed 15 people, and investigators said during testimony this week that parts of the investigation’s safety trail may have been shaped by a relaxed inspection schedule. The National Transportation Safety Board said a flaw related to the engine mounting area grew unnoticed before the aircraft lost an engine while accelerating down the runway.

The NTSB’s questions focused on how information and decisions moved among the airline, the aircraft maker and the Federal Aviation Administration, and on whether regulators and Boeing challenged the maintenance assumptions tightly enough. Aviation safety expert Jeff Guzzetti described the broader challenge for the agency as trying to parse out the roles and responsibilities of the three entities, with the intent of understanding what each contributed or failed to contribute.

The NTSB’s two-day hearing described how the engine mounting problem was difficult to see without detailed work because the relevant components sit deep near the pylons. The safety issue involved potential failures of a steel bearing and a metal sheath in the engine mount, which NTSB testimony said could ultimately lead to the lugs that secure engines to the MD-11 wings breaking.

Boeing officials acknowledged they had misunderstood the risks associated with those bearing and sheath failures before the crash. The planemaker pursued extending the required inspection interval for key engine mount parts after it sought to check them less frequently, and the FAA approved the request after a month-long review. Under the change, the inspection requirement extended from once every 19,900 cycles of takeoffs and landings to once every 29,260 cycles, according to the hearing testimony.

Investigators said Boeing supported the extension by relying on older data when it made the request in 2015. The NTSB testimony also said Boeing did not seem to account for seven instances on other planes of the same MD-11 model in which the key engine mount parts were failing. In the years following the schedule relaxation, the hearing testimony said three more instances were discovered before the crash.

The hearing also placed emphasis on what would have happened if the original schedule had remained in place. Testimony said the crash plane had flown 21,043 cycles at the time of the accident, meaning it would have been thoroughly inspected under the earlier requirements. The crash killed all three pilots and 12 people on the ground, and 23 others were injured, according to the testimony.

NTSB Chairwoman Jennifer Homendy said the FAA should have asked more questions when Boeing sought the inspection change in 2015. Homendy said the regulator knew the planemaker had sent out a service letter about the problem and had reported two of the issues earlier, even if regulators did not know all of the flaws that later surfaced.

Homendy questioned why the FAA accepted Boeing’s provided information without seeking more testing or further details. She said she was confused about why the FAA would not ask for more information and why it would accept information Boeing provided from certification decades earlier. Boeing’s Director of Airframe Service Engineering Justin Konopaske said Boeing should have shared the details it knew about with the FAA when it applied to extend the inspection schedule, while also saying the company did not have all records at the time of his testimony.

The hearing also included perspective from Greg Raiff, an aviation maintenance company owner who said plane operators are expected to follow federally approved maintenance schedules. Raiff said airlines would not be expected to reinvent their own inspection programs outside manufacturer design maintenance plans. He said that even if UPS and other operators feel “awful” about the accident, it is “not up to individual airlines” to change inspection requirements on their own.

The NTSB said it will continue investigating potential contributors to the crash before issuing a final report likely later this year or sometime next year. Meanwhile, FedEx resumed flying its MD-11s earlier this month after the FAA approved Boeing’s plan to ensure their safety, with testimony describing closely inspected engine mounts following the November crash and a forward-looking plan to replace spherical bearings regularly after every 4,000 cycles of takeoffs and landings. Homendy said the problems documented from 2002 to 2009 all occurred between 6,058 cycles and 13,650 cycles.