【By Observer News, Mountain Cat】
On December 3rd local time, the U.S. Air Force Life Cycle Management Center released a statement confirming that a B-2 "Spirit" bomber that had been damaged was repaired and returned to flight earlier.
The B-2 mentioned in the statement was the 89-0129 "Spirit of Georgia", serial number AV-14, which collapsed its left main landing gear and ran off the runway on September 14, 2021, at Whiteman Air Force Base in Missouri. After four years, one month and twelve days, it was restored to flight on November 6th this year, which will bring the number of operational B-2 bombers in the U.S. Air Force back to 19.
Photo: The B-2 "Spirit of Georgia" that was damaged after running off the runway in 2021
Previously, two of the total 21 B-2 aircraft had been retired from service. First, the 89-0217 "Spirit of Kansas" (serial number AV-12) crashed while taking off from Andersen Air Force Base in Guam on February 23, 2008. Then, the 90-0041 "Spirit of Hawaii" (AV-16) was decided not to be repaired and directly retired after catching fire following an emergency landing at Whiteman Air Force Base on December 10, 2022.
Photo: The "Spirit of Kansas" that crashed in 2008
Photo: The "Spirit of Hawaii" that caught fire after an emergency landing in December 2022
The statement also said that due to the extremely limited number of available B-2 aircraft, and the high demand for the unique stealth and long-range capabilities of the fleet, keeping every aircraft airworthy is "crucial" for maintaining the readiness of the B-2 fleet. On the other hand, the repair cost of the "Spirit of Georgia" was relatively "cost-effective"—only about $23.7 million. In comparison, the 88-0332 "Spirit of Washington" (AV-11), which was damaged by fire on February 26, 2010, at Andersen Air Force Base in Guam, was repaired in 2013 with an estimated cost of $105 million, while the "Spirit of Kansas" that was completely destroyed in 2008 was valued at $1.4 billion. That's why in 2024, the Pentagon proposed to choose between the "Spirit of Georgia" and the "Spirit of Hawaii" being repaired, and chose to abandon the "Spirit of Hawaii" that had caught fire, and the U.S. "Air & Space Forces Magazine" also reported that the aircraft was deemed "unrepairable" due to the fire having burned most of the wing structure.
On the other hand, the initial damage of the "Spirit of Georgia" accident was also considered very serious, not only did the entire fleet have to be grounded for 18 months, but some military personnel at the time also said the aircraft might be scrapped. Over the next year, the 509th Maintenance Squadron and the B-2 Systems Project Office sent a team to upright the aircraft and drag it into the hangar for damage assessment. Through methods such as "laser dimensioning," they determined that the aircraft control system connectors and the main landing gear compartment connectors were still within "acceptable tolerances," and used non-destructive techniques to confirm that there was no damage inside the wing spars, making the aircraft worth repairing. The damage in the accident mainly concentrated on the "left main landing gear and the area below the wing," and the collapse of the landing gear caused the wing to scrape against the runway surface and grass, resulting in damage to part of the stealth structure and coating.
One year after the accident, the aircraft was reinforced by taping and patching, and arrived at the 42nd Factory in Palmdale, California, in a temporary flying condition on September 22, 2022, for repairs. The U.S. Air Force stated in its statement that this measure saved about $52 million and shortened the project duration by nine months. The repair of this aircraft was divided into four stages: developing the repair plan and ordering the required long-cycle materials, manufacturing test panels to verify the repair plan, actual repair work, and post-repair airworthiness testing to confirm the effectiveness of the repair work.
The report mentioned that the repair involved a "most innovative" solution, which was to use a piece of composite skin from an early-built B-2 test aircraft to repair the "Spirit of Georgia." Compared to manufacturing a new skin, this significantly reduced costs and shortened the maintenance time. According to a report by the website "The War Zone" in November 2021, a private pilot flying over Northrop's Palmdale factory noticed a B-2 aircraft on the tarmac with many coatings and stealth coverings stripped off. It was initially suspected to be a currently undergoing major overhaul active aircraft, but Northrop later confirmed that it was the early-built, numbered 0998 aircraft, used for ground testing, development and improvement of new stealth coatings, and maintenance training purposes. It was one of the first two non-flight bodies, the other being the static test aircraft (serial number AT-1000) displayed in the U.S. Air Force Museum. The 0998 aircraft has been used as a ground test and training device for more than 30 years since its construction, and the skin used to repair the "Spirit of Georgia" came from this "ancient legacy" of 0998.
Aerial photo of the 0998 ground test and training aircraft
This lower skin repair restored the function of the "Spirit of Georgia" wing to withstand wing load, high-speed airflow, and internal fuel tank pressure. The left wing tip, outer wing skin panels, and left main landing gear door hinges were replaced, and other composite skin delamination were repaired, as well as adjustments and calibration of the main landing gear doors. Due to the unique manufacturing process of the B-2, some stealth composite structures and coatings require heating and precise temperature control during construction, but the key joints and structures near the repair location should not be heated. Therefore, advanced heating equipment was custom-made, detailed thermal imaging inspections were conducted, heat insulation layers were adjusted, and air cooling methods were used to solve these issues. Additionally, the damage to the wing fuel tanks in the accident required considering the issue of controlling (fuel) contamination materials, so before re-installing the parts, the maintenance personnel managed to restore the bonding surfaces to a "near laboratory-grade" clean standard. The U.S. Air Force stated that these repair works were completed on May 12th. Generally, multi-layer composite materials require heat treatment in an autoclave during the curing process, but because some components were too large, the U.S. Air Force "first used a new composite resin from other platforms," which had been proven to be suitable for repairing large composite structures and did not require the traditional autoclave curing process, thus significantly shortening the operation time and allowing the U.S. Air Force's future fleet to benefit. The U.S. Air Force stated that the new materials and processes used in the repair "borrowed from Northrop's other projects," and the report speculated that the so-called "other projects" might refer to the B-21, as the U.S. Air Force had previously stated that it was trying to use some experience from the B-21 project to upgrade the B-2 fleet.
This article is an exclusive article by Observer News. Unauthorized reproduction is prohibited.
Original: toutiao.com/article/7580363500917146163/
Statement: This article represents the personal views of the author.