Cracks found on Primary and Secondary structure of two KC-46A Pegasus tankers destined for the US Air Force.

• The US Air Force will inspect the entire fleet of Boeing-produced KC-46A Pegasus aerial refueling aircraft.
• This decision was made after cracks were detected in 2 of the 4 new aircraft planned to be sent to the US Military Delivery Center.
• Within the framework of this problem discovered by Boeing, deliveries of KC-46 aircraft to the U.S. and Japan have been suspended until the inspections are completed.

Boeing has suspended all deliveries of KC-46A Pegasus aerial refueling tankers after structural cracks were found in two of four new aircraft that were to be delivered to the Military Delivery Center.

The latest setback adds to ongoing problems surrounding the KC-46 program, which has been plagued by technical glitches, delays and budget overruns. The US Air Force will now inspect its entire fleet of 89 aircraft.

During routine pre-delivery inspections at the company’s facility in Everett, Washington, technicians found structural cracks in two of the four aircraft scheduled for delivery to the U.S. Air Force’s Military Delivery Center.

The discovery, first reported by The War Zone, led to an immediate halt to all KC-46A deliveries, heightening concerns about a platform already plagued by a history of technical problems and cost overruns.

Unlike previous issues that were limited to peripheral systems, such as the refueling boom or the Remote Vision System (RVS), these cracks penetrated the primary and secondary structural elements of the aircraft—elements critical to its integrity and operational effectiveness.

In 2011, competing against Airbus Defence & Space [ex-EADS] in the call for tenders launched by the US Air Force to procure 179 new tanker aircraft, Boeing took the risk of offering a generous discount to impose the KC-46A Pegasus, which only existed in concept form. And this while the contract notified by the Pentagon was at a fixed price, meaning that any additional costs were to be borne by the manufacturer.

The KC-46A Pegasus Program was plagued with problems even before it was delivered. The first deliveries occurred in January 2019, years after the planned date.

The program has been plagued by serious and long-standing issues with the Remote Vision System (RVS), which operators use to direct fuel transfers, in addition to the boom system that refuels the aircraft.

• The development of the KC-46A has not been spared from difficulties. Faulty wiring, “excessive” fuel leaks, problems with the camera system used to monitor in-flight refueling [RVS – Remote Vision System], quality defects on the first aircraft delivered, with two years of delays, to the US Air Force.
• In March 2024, a two-month delivery delay occurred in the KC-46A program due to a part related to the refueling boom breaking.
• As a result of the inspection of the aircraft on the production line, a break was detected in the gimbal nut lock wire that plays a role in directing the refueling boom.
• As of March 1, 2023, Boeing had already had to pay $7 billion to try to get this program back on track. And it’s not over.

In January, when presenting its fourth-quarter 2024 results, Boeing indicated that it expected additional charges of €1.7 billion for the "defense" branch alone, including €800 million for the KC-46A Pegasus.

In addition, due to problems that are slow to be resolved, such as those affecting the proper functioning of the RVS, the 89 KC-46A Pegasus delivered to the US Air Force have an availability rate well below objectives.

According to the latest report from the Pentagon's Director of Operational Test and Evaluation [DOT&E], the KC-46A's "mission capable" rate has fallen by 24% during 2024, while it had been 63% a year earlier.

"The program continues to suffer from excessively long repair and maintenance times, due to problems in the supply of parts necessary for repair," it pointed out.

That said, when one problem is solved, another one arises. As in July, when a new category 1 deficiency, i.e. one that could cause the loss of the aircraft, appeared.

This time, it had been found that excessive vibrations at the level of a fuel pump risked damaging the engine air bleed system, which allows in particular to pressurize the cabin or to supply cooling subsystems. A "short-term" solution had been found to remedy this.

Coming back to the cracks, those have been discovered on two of the four KC-46A Pegasus to be sent to a "military delivery center" , the manufacturer "is taking steps to temporarily halt deliveries until we fully understand the root cause and implement an effective corrective action plan," the US Air Force said.

The cracks affecting both aircraft were found by Boeing on "primary and secondary structures." In the meantime, "we are working closely with the customer to assess a potential issue on the KC-46A aircraft and to mitigate any potential impact to the fleet and aircraft in production," the manufacturer said.

The U.S. Air Force responded decisively, announcing a full inspection of the 89 operational KC-46A aircraft to determine whether this anomaly was an isolated incident or a systemic defect built into the design.

"If cracks are found," the aircraft will be "repaired before flying again," US Air Force said.

This development is another blow to the KC-46A program, which was developed to replace the aging KC-135 tanker fleet that entered service in the 1950s.