Sloppy maintenance culture, multiple errors caused F-22 to overheat, investigation finds

(INTERJECTION: This incident is SO FAMILIAR –ref. “A Near Miss – And How Many More Unreported?” concerning a similar maintenance error, but in nuclear maintenance, that could have obliterated the island of Puerto Rico, most people on the island and myself, plus WW III, Starting on Page 4 ~ Don Chapin, Capt., USAF, Ret’d)

By Rachel Cohen
Fri Jul 9 2021 2:41 PM
An F-22 Raptor fighter jet assigned to the 422nd Test and Evaluation Squadron sits on the ramp at Nellis Air Force Base, Nev., in June 2019. (Airman 1st Class Bryan Guthrie/Air Force)

Multiple maintenance errors, unsafe unit culture and leadership failure caused an F-22 Raptor to overheat while it was in the shop at Nellis Air Force Base, Nevada, last fall, costing $2.7 million to repair, according to an investigation report released Friday.

The advanced fighter jet, assigned to the 422nd Test and Evaluation Squadron at Nellis and maintained by the 757th Aircraft Maintenance Squadron, suffered a series of oversights and incorrect procedures while airmen overhauled the airframe to prepare it for new operational test missions.

Part of the jet’s auxiliary power unit was removed two days before the Oct. 30, 2020, accident so airmen could troubleshoot one of the modifications, the Air Force said. That auxiliary unit is an engine that provides electrical and hydraulic power to a plane for ground operations.


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But maintainers did not correctly label the relevant circuit breakers with a “REMOVE BEFORE FLIGHT” tag or add the right warnings to the aircraft or its digital paperwork as called for by the repair manual.

When the mishap occurred, the auxiliary power unit’s emergency off switch was incorrectly set to ‘normal,’ the service said in a news release Friday. One maintainer turned on the power while defueling the aircraft, without realizing an exhaust duct still needed to be installed to let out excess hot air.

“Once the [power unit] was started, hot exhaust gas flowed directly into the exhaust bay rather than being diverted out of the aircraft,” the Air Force said. “With smoke emanating from the exhaust bay, the maintenance member selected the wrong course of action by making an improper attempt to run diagnostics and review fault- reporting codes.”

That allowed the Raptor to overheat longer, until another maintainer manually shut down the power source.

“The [F-22] sustained damages to airframe, systems, wiring, hydraulics and surrounding structure and components of the … exhaust bay from an overheat event,” the report found. “Temperatures within the exhaust bay reached 600-700 degrees Fahrenheit for less than 10 minutes.”

Several maintainers failed to prevent the incident, the report said, including a supervisor who was onsite to check the work of another airman but did not correct their mistakes. Investigators also noted the Nellis airmen were distracted by a morale-booster day with a VIP visit and a flight demonstration, leading them to overlook certain steps.

Air Force maintainers brace to meet Mattis’ 80-percent readiness order

Defense Secretary Jim Mattis has thrown down the gauntlet for the Air Force’s maintainers: Get four out of every five F-16, F- 22 and F-35 fighter jets ready to fly at any given time. It’s not going to be easy. (A repeat of SAC’s “ALERT” force during the cold war. ~ Don Chapin)

Leading up to the accident, various airmen performed inspections they were not qualified to do, did not realize the exhaust duct needed to be installed, failed to properly fill out the maintenance paperwork and put visual reminders of remaining work on the airplane, and disagreed on the right way to take fuel out of the jet.

All but one of the unit’s maintainers who serviced or inspected the aircraft were fully trained and qualified, the report said.

“At the time of the mishap, there was no one formally assigned to provide oversight of the [F-22] and its forms beyond standard production personnel,” the report added.

The F-22 had 51 “red X” events in its records, indicating the “most serious possible condition: that the aerospace vehicle is unsafe, unserviceable or non-airworthy,” the report said. Yet the jet was towed between hangars and powered up against service guidelines.

Maintainers correctly noted installation warnings for F-22 exhaust ducts in only about one-third of the times when they were removed in the year leading up to the incident, investigators found.

“If maintenance crews correctly executed proper maintenance procedures in accordance with [technical order] guidance, this mishap would not have occurred,” the report said.

About Rachel Cohen

Rachel Cohen joined Air Force Times as senior reporter in March 2021. Her work has appeared in Air Force Magazine, Inside Defense, Inside Health Policy, the Frederick News-Post (Md.), the Washington Post, and others.

A Near Miss – And How Many More Unreported?

Date: Early ’60’s; Place: A nuclear weapons maintenance facility at an Air Force Base on an island in the Caribbean; Author: Don Chapin, Capt., ret.


At this time, long after the cold war has ended, we are now hearing about some of the various operational situations, both American and Russian, where we have been just seconds away from missile launches because of radar “bogies” or false electronic information. Very few have really mentioned the fact that every-day life at the technical level around nuclear weapons can also be a problem.

As an electronics technician in the special weapons field (which it was called at the time) in USAF’s Strategic Air Command (SAC), I have run across and heard of a number of near misses of nuclear- related “incidences” in the field (some of which are documented). But, this one in which I was personally involved was, by far, the worst of those incidences of which I have direct knowledge. Yet, considering the circumstances, I would strongly suspect that it was/is not an isolated situation. While there (hopefully) have been advances in technology and operational support to preclude repeat situations of this magnitude, considering the spin that has become typical for political purposes, apparently including within the military, I would hesitate to accept any assurances that situations such as the following cannot be repeated to some extent.


The Ramey AFB Incident:

There were three of us in the maintenance building: a senior master sergeant (the NCOIC) in the
front office, a SSGT technician in the south maintenance bay doing a Final Assembly Test (FAT) on a thermonuclear weapon which had about 180 (to 500, depending upon information source) times the capability of the Nagasaki bomb (about 20KT), and myself in the center bay, working on spares inventories.

Suddenly, the SSGT burst through the maintenance door, yelling, “RUN, IT’S TICKING.”

The three of us ran out the front door and, knowing we didn’t have the time to get any further, we tried “covering up” in a shallow ditch across the road from the facility. We had NO idea what was going on inside the weapon… whether it might go full TN (thermonuclear) capability (in which case we and some of the base would be vaporized, and the island a full-scale disaster area, far worse than Nagasaki), full HE (high explosive, without the atomic-TN chain going), or low-order HE with just some of the explosive going off, in which case we MIGHT live through it.

There were seven critical “switches” in this particular weapon, some for safety but most for operational applications, and I could visually place each of them as I had given classes on that fuzing and firing circuit to our other technicians (and “fuzing” is the correct spelling).

After about five minutes – the longest minutes in my life – we decided that it wasn’t going to blow in any of those modes, so we (very weakly) crawled out of that ditch to reenter the building and initiate the necessary reporting. It was then that the SSGT, who had been acting in the capacity of a technician, related what had happened.

During the FAT, using the T-138 portable test set with a rotary selector switch for specific functions, the sequence for this weapon was to plug both test cables into the top receptacles and go through specific test steps. The cables were then pulled from the top receptacles and one of them plugged into the side receptacle for an additional set of tests. This cable was then extracted from the side receptacle and both cables then re-inserted into the top receptacles for the last test steps.

However, in this case, the SSGT, “in order to save a little time” (and probably because the Mk 36 was a larger weapon diameter), left the second cable in the top receptacle when he pulled one cable from the top and plugged it into the side receptacle… a very clear checklist procedure violation. Then, when he rotated the tester selector switch, he heard “strange noises” inside the weapon, whereupon he rapidly exited the maintenance bay and shouted the warning.

Naturally, even though we could have torn the weapon apart to do our own postmortem, we were not “qualified” to do so and had to send the weapon back to Albuquerque, NM, for the tear-down and analysis.

Several weeks later we received a very abbreviated result – of those seven critical “switches,” in the weapon, six had “fired,” in sequence, for a full thermonuclear surface burst. Therefore, only one “operational” switch had not closed and that was simply because it was normally pre-set to a position where it was up to the orders received by the aircrew, immediately prior to “delivery,” as to where it was to be positioned. It was that particular switch that I had “set” in a hardware bench test a day earlier. That was how close we were to a very major disaster. (Ref. the NOTE-1 incident)

Now, if that weapon had gone off (and Ramey was known to be a high-priority SAC base during the cold war, i.e., on the USSR’s target list), who would have realized that it had happened because of somebody not following a checklist and that there was no intentional sabotage or “enemy action” that required a retaliatory response?

Just a couple of weeks after the results of that weapon tear-down was announced, the Strategic Air Command (SAC) initiated their well-known Two-Man Policy for nuclear weapon access: (paraphrased) ANY time there is a human presence around a weapon there had to be at least a second person there as well, of equal knowledge with respect to weapon operation. The theory was that this would preclude another incident such that with which we were involved. This policy has long since morphed into the USAF no-lone-zone policy, Air Force Instruction 91-104 and AFPD 91-1, Nuclear Weapons and Systems Surety, now addressed as the more politically correct “Two Person Policy.”

It should be noted that neither this “incident,” nor a B-47 crash- and-burn at Whiteman AFB in the late ’50s (when I was stationed there, and similar to the NOTE-2 incident) are listed in the List Of Military Nuclear Accidents, from,, or any other website.

The full aircrew was also lost in the Whitemen crash (they were burned alive), because the fire department was so concerned about the potential of a large explosion with a Mk6/Mod6 on board. How many other “Broken Arrow” incidents have never made it into public records? MANY!!! Why??? The military branches don’t want this publicized!!

Personnel Selections & Speculations:

USAF enlisted personnel assigned to the special weapons field were initially in the 96-98th percentile group of all enlistees, had a minimum of a high school diploma and, preferably, already had some degree of electronics knowledge. However, such selection criteria, obviously, does not preclude anyone in that group from accomplishing a normal, human,

d _ _ b-a _ _ action.

However, in the time I was in that field, I saw it being rapidly “watered down” with higher ranking enlisted personnel that had no concept of what it meant to have to “stay current” with technical manuals that were written at the 5th-year college level or higher (example, the above-mentioned senior master sergeant, who also had many psychological problems). When I had only two, then three stripes, I often had the responsibility of “training” a senior NCO that wanted to cross-train into the field, often because of the “prestige,” but who had no interest in listening to someone of a junior rank, nor had the capability of deciphering those tech manuals. The obvious implications are…

Getting back to the global stage, what about these other countries that are developing a similar capability? Where are they going to get the reliable personnel to properly maintain their stockpile(s)? … And what would happen if one of their weapons went off in a similar manner… without traceability, who would be blamed?


NOTE-1, from

January 24, 1961, Goldsboro, North Carolina

In what nearly became a nuclear catastrophe, a B-52 bomber on airborne alert carrying two nuclear weapons broke apart in midair.

The B-52 experienced structural failure in its right wing and the aircraft’s resulting breakup released the two weapons from a height of 2,000-10,000 feet. One of the bomb’s parachutes deployed properly and that weapon’s damage was minimal. However, the second bomb’s parachute malfunctioned and the weapon broke apart upon impact, scattering its components over a wide area. According to Daniel Ellsberg, the weapon could have accidentally fired because “five of the six safety devices had failed.” Nuclear physicist Ralph E. Lapp supported this assertion, saying that “only a single switch” had “prevented the bomb from detonating and spreading fire and destruction over a wide area.”



NOTE-2, from

Lakenheath Air Base, Suffolk, England – July 27, 1956

A B-47 bomber crashed at Lakenheath Airbase in Suffolk, England. While the bomber carried no nuclear weapons, it hit a concrete nuclear weapons storage bunker known as the “igloo,” where three U.S. Mark VI nuclear bombs — the same type of bomb dropped on Nagasaki — were stored. In the collision, three of the bombs sustained damage that could have resulted in detonation. In explaining the accident, Gen. James Walsh, commanding officer of the U.S. 7th Air Division in England, sent a brief cable to Gen. Curtis LeMay, commander of the U.S. Strategic Air Command. “Aircraft then exploded, showering burning fuel over all. Crew perished. … Preliminary exam by bomb disposal officer says a miracle that one Mark Six with exposed detonators sheared didn’t go.”



And about 30 years later??

Extracted from:, 717 MUNSS NUCLEAR SURETY WEAPONS SAFETY LESSON PLAN, Revised 10 Nov 94, Volkel AB, Netherlands (and also cited by Greenpeace).


“It is important that we learn from our past mistakes. Here are some examples of past accidents/incidents and how we have learned from them.
“PRP (Personnel Reliability Program) – An individual was given very strong medication but wasn’t taken off PRP. He reported to work the next day very “high” from his new pain killers and failed to inform anyone. This condition went undetected by fellow workers and supervisors. While performing his duties he caused major damage to a weapon system because he was just too drugged up to pay attention. This could have been prevented very easily. The person giving the medication should have annotated his medical records and notified someone in the individuals chain of command. His co- workers should have detected his unreliable condition. This must never be allowed to happen again.

“Tech Data – A Weapon Loading crew was conducting a loading operation when they failed to closely follow the specific technical data. A weapon was subsequently incorrectly hung and later fell on the runway, cracking the case. There is no excuse for not using tech data. This accident could have had international repercussions. We were lucky. People need to be aware of the awesome responsibility they have, no matter what there (their) job is. Everyone has a role.

It has happened before and it can happen again. Please, don’t be the one who makes the fatal mistake due to carelessness.”

The first incident under the “PRP” can be classified as either a “Bent Spear” or a “Broken Arrow,” but also IS NOT listed in the “List of Military Nuclear Accidents.”

I remember a situation where one of our mechanics, who was renown for his tractor and tug skills in handling nukes in and out of the revetments, one day simply couldn’t seem to get anything right, banging the weapons and carriages around to the extent that we became quite worried. Asking him what his problem was, he simply replied that this was the first day in over a year that he had come to work sober! – Don

Again, the incident under “Tech Data” can be classified as either a “Bent Spear” or a “Broken Arrow,” but also IS NOT listed in the “List of Military Nuclear Accidents.”

Here we go again! If this had been a MK 5 or 6 series, that facility could have instantaneously had some real trouble! – Don



“… according to a General Accounting Office (GAO) report entitled Navy Nuclear Weapons Safeguards and Nuclear Weapon Accident Emergency Planning, a total of 563 nuclear weapon incidents were reported by the Navy between 1965-1983.” Further:

“While studies by non-governmental organizations such as Greenpeace often cite many more accidents, even DoD’s conservative estimates document that at least one serious nuclear weapon accident occurred every year. This should give pause to any policymaker considering the future utility of nuclear arsenals.”

And this is simply referring to those that are reported!


“To the rulers of the state then, if to any, it belongs of right to use falsehood, to deceive either enemies or their own citizens, for the good of the state: and no one else may meddle with this privilege.”



These are DoD incident designations…but each service re-interprets them in their own way.


* A nuclear weapon system incident

* significant incident or unexpected event involving a nuclear weapon, warhead, or nuclear component resu1ting in damage to the extent that major rework, examination, recertification, or complete replacement by the design agency is required.

* an incident requiring immediate action in the interest of safety or nuclear weapons security which map result in adverse national or international public reaction.


* A nuclear weapon system accident

* an unexpected event involving a nuclear weapon, warhead, or nuclear component resulting in destruction of a nuclear weapon, radioactive contamination, or a hazard to the public either actual or implied, such as nuclear or non-nuclear detonation of a weapon.

======================================================= =======================================================

NAVAL NUCLEAR ACCIDENTS (a Greenpeace report), from:


The Nagasaki weapon, Little Boy, was a gun type using Uranium

The Hiroshima weapon, Fat Man, was an implosion type, using Plutonium

“Modern” Nuclear Weapons use – from:

“Tritium (H3, a nucleus of one proton and two neutrons, vs. one proton) is (now) widely used in nuclear weapons for boosting a fission bomb or the fission primary of a thermonuclear weapon. Before detonation, a few grams of tritium-deuterium gas are injected into the hollow “pit” of fissile plutonium or uranium. The early stages of the fission chain reaction supply enough heat and compression to start DT fusion, then both fission and fusion proceed in parallel, the fission assisting the fusion by continuing heating and compression, and the fusion assisting the fission with highly energetic (14.1 MeV) neutrons. As the fission fuel depletes and also explodes outward, it falls below the density needed to stay critical by itself, but the fusion neutrons make the fission process progress faster and continue longer than it would without boosting. Increased yield comes overwhelmingly from the increase in fission; the energy released by the fusion itself is much smaller because the amount of fusion fuel is much smaller.

“Besides increased yield (for the same amount of fission fuel with vs. without boosting) and the possibility of variable yield (by varying the amount of fusion fuel), possibly even more important advantages are allowing the weapon (or primary of a weapon) to have a smaller amount of fissile material (eliminating the risk of predetonation by nearby nuclear explosions) and more relaxed requirements for implosion, allowing a smaller implosion system.

“Because the tritium in the warhead is continuously decaying, it is necessary to replenish it periodically. The estimated quantity needed is 4 grams per warhead.[11] To maintain constant inventory, 0.22 grams per warhead per year must be produced.

“As tritium quickly decays and is difficult to contain, the much larger secondary charge of a thermonuclear weapon instead uses lithium deuteride as its fusion fuel; during detonation, neutrons

split lithium-6 into helium-4 and tritium; the tritium then fuses with deuterium, producing more neutrons. As this process requires a higher temperature for ignition, and produces fewer and less energetic neutrons (only D-D fusion and 7Li splitting are net neutron producers), LiD is not used for boosting, only for secondaries.

Controlled Nuclear Fusion

“Tritium is an important fuel for controlled nuclear fusion in both magnetic confinement and inertial confinement fusion reactor designs. The experimental fusion reactor ITER and the National Ignition Facility (NIF) will use Deuterium-Tritium (D-T) fuel. The D-T reaction is favored since it has the largest fusion cross-section (~ 5 barns peak) and reaches this maximum cross-section at the lowest energy (~65 keV center-of-mass) of any potential fusion fuel.”





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