https://www.ainonline.com/aviation-n...ource=hs_email

NTSB Final:
https://data.ntsb.gov/carol-repgen/a...ort/103452/pdf

Left wing separated inflight on this King Air C90 Fire Fighting support aircraft. A crack discovered during NDI generated a recommendation from Textron to replace the wing spar, instead it was patched.

The repair, which involved enlarging the hole and installing a doubler around it, was approved by an FAA-designated engineering representative (DER). The DER claimed no knowledge of the communication between Textron Aviation and the maintenance provider about the crack, though the maintenance provider alleged otherwise.

 

Things like this make me appreciate 21st century 121.

 

The AIN article, and NTSB findings, are problematic in this case, for several reasons.

Reference to direction from Textron suggests that manufacturer direction was the only appropriate action, when this is not the case. It's a daily occurrence in aviation for manufacturers to want something done their way or by them, nearly always at a much higher cost than could be done by other means, and it's a very common occurrence by nearly every operator in the world to use other means. The FAA has long held that if a manufacturer wants to require something, they need to push for it to be an emergency AD, something that manufacturers are loathe to do, for fear of damage to reputation of the company and the product. Instead, manufacturers will issue direction in many forms, including "mandatory" service bulletins and other means. The FAA maintains that a manufacturer saying something must be done, even by adding terms like "mandatory" to the direction, does not make it so. The article, and the NTSB report, use the manufacturers "recommendation," and "requirement" and "advice" to suggest that the operator, Falcon Executive Aviation, did wrong.

Whether Falcon Executive did or did not do wrong, it wasn't because the operator failed to do what the manufacturer wanted to do. Whatever operator anyone reading this works for, I guarantee that maintenance has been performed on the aircraft you fly that is not what the manufacturer recommended or wanted, but is an alternate means of compliance (most often, in the case of structural repairs, involving a designated engineering representative). This is standard, and normal, routine means of effecting repairs involves direct compliance with manufacturer data (eg, structural repair manual, etc), or alternate means that range from STC kits to engineered repairs. The article and NTSB report insinuate otherwise, inferring wrong doing by failing to replace the spar cap.

It's notable that despite all reference to the engineered repair, NDT testing, etc, that the wing separation occurred at another point than the repair. The repair was inboard of the separation. This is nearly glossed over in both the article and report

https://www.ainonline.com/aviation-n...ource=hs_email
The reports that the spar cap (the article uses spar and spar cap interchangeably, which is not true) repair are central to the failure infer that the cracking originated at the spar repair and thus, was a faulty repair that caused a wing separation. Not only is this a big leap, but it's false. Much is made of the repair, and the reader might be forgiven for thinking the repair failed and the wing was lost, but that's not true. At best, an indirect inference is made; the supposition being that had the entire area been replaced and not repaired, the failure point that did cause the wing loss, would have been discovered. This is speculative at best; if Falcon Executive (et al) had replaced the spar, or spar cap, or the wing, or the entire airplane, then theoretically there would have been no crack, but thats not the issue; the issue is that most of the reporting in the article and in the NTSB report focuses on the repair, which was not shown to cause the wing loss or failure. It wasn't the repair, and it wasn't a crack propagating from the repair.

https://data.ntsb.gov/carol-repgen/a...ort/103452/pdf
The crack that is believed to have caused the wing loss did propagate but wasn't associated with the repair. Focus on the repair is a red herring.

The NTSB report states:
After much ado is made of the DER-approved repair, the NTSB states that they never found the repaired area, and it was never examined. What follows is the crux of the argument, which is that had Falcon Executive followed manufacturer recommendations, the entire area would have been removed and replaced. This does NOT mean, however, that the crack would not have occurred, had the manufacturer recommendation been followed.

Some years ago, I was asked to take over maintenance on a King Air, and after an initial review of the aircraft and paperwork, I discovered missing inspections; I advised the owner that I wouldn't assume the role until the airplane was brought current at a Beech facility. Consequently, with the owners approval, I took the airplane to a beech approved repair station. The initial inspection yielded a quote that exceeded the value of the airplane, and the owner asked me to go to the repair station and knock half the cost off the bill. I did a thorough review of the repair station's findings, and initially reduced the bill by about 300,000. This wasn't winnowing down repairs that we thought we could get away with. This was unnecessary work that didn't need doing. Replacing a windscreen panel for delamination that was well within tolerance; replacing an oil return tube for a dent that was well within tolerance, etc. Manufacturers would absolutely love every repair to be made by replacing an item with new parts, but there's a reason that most of the tires on your aircraft are re-treads, the brakes are remanufactured and overhauled; even main windscreen panels are often refurbished, remanufactured, overhauled, or are replacements not made by the manufacturer. The same is true of most of the components on nearly every aircraft. There's a reason that tolerances exist, else none of us would ever fly.

I have no issues with calling out a faulty repair. That was not the case here. I have no issues with calling out a repair that failed. That was not the case here. I have no issues with citing improper materials, workmanship, bad engineering, or failure to complete the designated repair in accordance with a approved data. None of these are the case here, either.

I do have an issue with building a case that is a red herring or smokescreen that obscures the actual issue, and that is very much the case here.

I spent a lot of years firefighting, and am intimately familiar with wing failures that have occurred over fires. This particular failure was quite different. The mission wasn't a low level lead operation, but a higher-altitude air attack mission, orbiting the fire. Fairly gentle turns, low speed maneuvering, circling a fire area. Fire aircraft experience stresses and damage at a much higher rate (500-1000 times higher, according to NASA) than the aircraft might in commercial service, so stress-related cracking and damages aren't unexpected, hence ongoing testing on the airframe that failed. When so much emphasis is put on an approved repair, as is the case with this article, when the repair didn't lead to the crash, , and the repair itself coudln't even be located or examined, is more than a stretch. It's unprofessional and inappropriate. It's one thing to suggest that the crack should have been found: obviously with any failure, this is the case, but to point to the repair, and to make inferences that various parties are less than truthful (in absence of any evidence) is poor investigating and poor reporting.

 

I tend to agree with JB, it wasn't apparent that there was a clear link between the repair and the failure. Unless the mfg had good reason to believe that crack they were addressing was indicative of overall excess fatigue and un-serviceability of the spar... that's not clear at all and as JB points out the mfg is not the ultimate authority. They have a clear conflict of interest, ie their economic interest before the operators economic interests.

Still glad I'm in 121. Although there have been at least a couple of catastrophic botched structural repairs of foriegn airliners in the distant past.

Now lets see what UAL does with that 767...

 

This is third hand information but the one in IAH is going to be repaired.