FAA issues AD to address potential Boeing KC-46 critical function loss

The United States Federal Aviation Administration (FAA) is issuing an airworthiness directive (AD) to address a potentially unsafe condition on the Boeing KC-46 Pegasus, a military aircraft based on the Boeing 767-200.

The FAA said that it had “received a report of an arcing event on an electrical terminal lug in the P34 panel that caused heat and smoke damage within the panel”. Following an investigation into the matter, it was found that the arcing was caused by a “loose power feeder terminal lug connection” and the agency highlighted that the terminal lug was “not torqued to the required specifications”.

After additional inspections, the FAA went on to identify “multiple findings of under-torqued terminal lugs” and determined that it “could result in arcing that may lead to loss of critical function and loss of continued safe flight and landing” if the condition was not addressed.

The AD, which was published on April 4, 2023, is effective from April 20, 2023, and is a final rule.

Workmanship issue
The FAA noted that, since this is “a workmanship issue”, the AD will not affect the Boeing 767F, which is manufactured at the same facility in Everett, Washington.

To address the condition, operators will have to visually inspect electrical terminal lugs, wires, and attached components in certain electrical power panels for electrical arcing damage, and repair or replacement of any damaged part. The FAA also mandated a “detailed inspection of each terminal lug for loose lugs in certain power panels, and retorquing each loose terminal lug”.

In total, the cost of compliance is $3,655 per inspection cycle consisting of 43 work hours valued at $85 per hour. According to the regulator, there are no US-registered KC-46s affected by the AD. On-condition costs, namely the removal and replacement of terminal lugs and the torquing of the lugs, each action will take one work hour at a cost of $85 per hour.

The FAA noted that operators of the KC-46 must carry out a “general visual inspection (GVI) for electrical arcing damage of electrical terminal lugs, wires, and attached components in certain power panels, and before further flight, repair any damage found”. They will also be required to complete a “detailed inspection of each terminal lug for loose lugs in power panels, and, before further flight, apply torque to each loose terminal lug”.

The action must be completed within 10 months of the effective date of the directive.

Boeing had previously suspended deliveries of the KC-46 and Boeing 767F due to an issue with the aircraft’s center fuel tanks when a supplier failed to follow the proper cleaning and paint adhesion procedures. This resulted in the potential clogging of the fuel filter, restricting the flow of fuel to the aircraft’s engines.

The manufacturer resumed deliveries of both aircraft in March 2023, handing over one 767F to FedEx Express, registered as N283FE, and a KC-46 to the United States Air Force (USAF), registered as 19-46007. Both aircraft were delivered on March 24, 2023.

Riddled with problems
The KC-46 program has encountered a number of problems and Boeing was forced to book charges related to the program totaling billions of dollars.

For example, prior to its first delivery to the USAF in January 2019, it was discovered that the Remote Vision System (RVS), developed by Rockwell Collins, was not working properly. Further problems followed, including issues with the fuel boom, improperly working cargo hold fasteners, and excessive fuel leaks.

Throughout 2019, deliveries were suspended twice due to quality concerns. The USAF found loose tools and other foreign object debris (FOD) in its KC-46s due to the “manufacturing discipline issue,” according to then-Secretary of the USAF, Heather Wilson.

Since Boeing has a fixed price contract with the US government on the KC-46 program of $4.9 billion, this means that any additional costs could result in Boeing recording “an earnings charge and/or provide refunds to the U.S. government,” read the company’s Q4 2022 report.

In 2022, Boeing booked a total of $1.3 billion of charges related to the KC-46 program, while in 2021 the amount was $402 million. In total, Boeing has booked $6.8 in charges since 2011. That number is set to go up due to the center fuel tank issue. During the Bank of America Global Industrials Conference on March 22, 2023, the Chief Financial Officer (CFO) and Executive Vice President of Boeing Finance said that the company will book another charge, presumably to be announced during the company’s Q1 2023 result presentation.

Boeing is scheduled to hold an annual investors conference on April 18, 2023. While the manufacturer is yet to announce the publishing date for its Q1 2023 results, its Q1 2022 results were announced on April 27, 2022.