Aircraft Accidents and UAS Data, Part VII

Well, it is official: we have become a civilization of uncommunicative idiots. Don’t believe it? The next time you’re in a restaurant … any restaurant, take a look around; people are not engaged in conversation; they are looking at their cell phones; surfing social media and texting. The ability to converse with our spouses, parents, children, etc. has escaped us. In a crowd, we are solitary figures, just like Paul Simon sang about in “I Am a Rock”. And the inability is leaking into our professional conversations, just when we need to keep the lines open.

The unmanned aerial system (UAS) conversations, to date, have always been monopolized by lobbyists and the inexperienced – often the same people. They make ridiculous assumptions, dodge facts, employ sarcastic reasoning and take shots at their ‘opponents’ as if the conversation were an adolescent game. When professional courtesy is not offered, it is not returned, on either side of the argument. However, problems long unaddressed, still exist.

Fortunately, a UAS and the national airspace system (NAS) conversation has been cultivated by serious-minded people. A fourth study Article has been written by Ryan Wallace, Kristy Kiernan, John Robbins, all of Embry-Riddle University; Tom Haritos of Kansas State University and Jon Loffi of Oklahoma State University, titled: Evaluating Small UAS Operations and National Airspace System Interference Using AeroScope. The Article was printed in the Journal of Aviation Technology and Engineering 8:2 (2019) 24-39. In the four studies the Authors keep moving the conversation forward, providing invaluable data to promote practical solutions.

The first sentence in the report states, “A recent rash of near mid-air collisions coupled with the widespread proliferation of small unmanned aircraft systems (sUAS) raise concerns that integration is posing additional risk to the NAS”; a brief, common sense problem statement. Until both sides of the argument can accept this fact and stop transferring blame to any culprit, from President Trump to Climate Change, we will never solve the real problems. The Authors looked at and compared many factors to aid their data-seeking.

“In this study, the authors partnered with a UAS technology company to deploy an AeroScope, a passive radiofrequency detection device, to detect UAS flight activity in an urban area.” The Authors employed the latest technologies in their study. However, even with the most advanced tracking system, the ‘Bad Apples’ are still successful at playing Hide-and-Seek, mostly because, as the study highlights, the technology is not commonplace in the field yet.

The report stated that while this technology was used in a limited area, “The authors assessed 93 potential violations of 14 Code of Federal Regulations (CFR) Part 107 regulations, including controlled airspace breaches, exceeding maximum flight altitudes, and flight outside of daylight or civil twilight hours.” These are sobering findings. The regulation-busters are not disciplined professionals, e.g. aerial photographers, realtors, they are amateurs, people who represent the UAS industry’s ‘Bad Apples’. And while the UAS industry must deal with its own lawbreakers, the law makers need to get their joint houses straight before the circular firing squad sets up.

Three situations to consider: 1 – the Federal Aviation Administration (FAA) has been given responsibility for the UAS industry. 2 – Prior to this writing a UAS entrepreneur applauded the Daytona Police Department for their professionalism in dealing with drones. 3 – Tim Bennett, Program Manager for the Department of Homeland Security (DHS) Science and Technology Division, recently spoke to NBC News, confirming what had been stated repeatedly: that drones are a threat to passenger jets near airports. The NBC reporter also spoke to entrepreneurs generating technology that finds drones being flown illegally. Other technologies are being designed to bring those drones down.

The FAA, a local police department and the DHS, each involved with unmanned aerial vehicle, aka drone traffic. This represents major attention at drones, but who has ultimate authority? The FAA has authority in the NAS; the local police in communities below the NAS, e.g. indoor arenas, city streets, while DHS has authority of terrorist prevention. Then there is the Federal Bureau of Investigation (FBI), the military, the Secret Service, etc., all with their own jurisdictions. Kind of like when two outfielders call the fly ball, only to have it drop between them in the confusion. The truth is the UAS industry needs all the supervision it can get because the UAS is not like anything else we have seen; it mixes professionals with amateurs, each wanting to penetrate the NAS. Wait until flying cars and aerial taxi services enter the fray.

One may suggest that the more eyes, the better. However, jurisdiction is a funny thing, funny in the way that it can get laughable. Add to the confusion the introduction of cooperating government agencies; the concept is an oxymoron, e.g. jumbo shrimp or pretty ugly, which is how a jurisdiction issue could end up.

There was a promising point in the NBC report: entrepreneurs developing technology. The Authors partnered with a UAS technology company to … What? Find a solution to a problem that they both shared. Does anyone else see solutions? Recently I took part in a discussion where the theme was that the FAA failed the UAS community. I stated, “If the UAS industry is waiting for the FAA to create the UAS technologies, they will have a long wait. The FAA does not have the manpower, money, time, expertise, etc. to meet the task.

The UAS entrepreneurs, who know the technology and the capabilities, must step up, create the means to track and. if necessary, police their own.” The rest of the aviation industry does this; they have been doing this for decades, e.g. discovered solutions to Stage III noise reduction or improved engine reliability for twin-engine overwater flights. The aviation industry policed their own safety programs, e.g. air operators auditing those who are contracted to them. They built better mouse traps and have opened their world globally.

The UAS industry has the money, risk-takers and technologies to accomplish these things. They must weed out the bad apples and prove to the other NAS users they belong there. The studies are a first step to understanding the need and represent the blueprint for pursuits in multiple directions; they are footwork already trod. The UAS industry needs to decide to take the next steps and keep those communications going.

Aircraft Accidents and Lessons Unlearned XXV: FedEx 910 and FedEx 630

On October 28, 2016, at 17:51 eastern standard time, the left Main Landing Gear (MLG) of N370FE, FedEx flight 910, an MD-10-10 freighter (F), failed, then collapsed, during rollout after landing in Fort Lauderdale-Hollywood International Airport. Damage to the wing and subsequent rupture of fuel lines and tank, led to a post-crash fire.

FedEx operates two different DC-10 types in its fleet: the DC-10-10F and the DC-10-30F; both were converted to the MD-10 series. The MD-10-10F is a short-range version because it has no auxiliary fuel tanks. All FedEx’s MD-10-10Fs previously flew for other airlines, mostly passenger.

According to the report for FedEx 910, accident number DCA17MA022, the approach and landing were uneventful; the aircraft did not sustain a hard landing; pilot error was not to blame. The post-accident investigation report revealed that a major contributor to the accident was the left MLG outer strut cylinder failed due to an overstress fracture: “a small thumbnail crack, located at the radius between the cylinder inner diameter surface and the air filler valve bore (AFVB) surface,” located at the top of the strut.

In Memphis, July 28, 2006 (ten years prior), FedEx 630, accident number DCA06FA058, an MD-10-10F, crashed on rollout with a near identical left MLG failure. The timeframe for both accident aircrafts’ MLG, between overhaul and accident, matched: FedEx 910’s left MLG was overhauled 8 years, 8 months prior to its accident; FedEx 630’s left MLG was overhauled 8 years, 6 months before its accident.

Following the 2006 FedEx 630 accident, FedEx, Boeing and the Federal Aviation Administration (FAA) acted quickly. FedEx immediately inspected all MD-10 MLG cylinders for defects per Boeing’s Alert Service Bulletin (ASB) DC10-32A259. Boeing also issued a revision to the Component Maintenance Manual (CMM), requiring video probes and eddy current inspections of the air filler valve bore. The FAA issued Airworthiness Directive 2008-09-17 supporting the ASB and CMM revision. FedEx was the only domestic MD-10 large operator, with thousands of MD-10 flights per year. Neither McDonnel-Douglas’s aircraft design nor FedEx’s maintenance program were the cause. The National Transportation Safety Board (NTSB), however, never looked beyond the MD-10.

Both investigations found that the MLG cylinders failed because stray nickel plating was introduced into the AFVB. According to FedEx 910’s accident report, nickel plating with a thickness of 0.008-inch thickness “results in a stress factor increase of 35%”. During the left MLG cylinder’s in-service lifetime, a load event “compressively yielded” the AFVB material, “causing a residual tension stress”. In layman’s terms, the nickel-plating process somehow weakened the cylinder metal’s integrity in the AFVB area. The residual stress led to fatigue cracking.

There are two troubling issues about these accidents. First, is that both accident reports DCA06FA058 and DCA17MA022 were written in a field accident (FA) report format, similar to a General Aviation report – not in a standard major accident (MA) report format. In other words, there was minimal deserved attention to these accidents. Neither accident had a hearing; they had an inadequate number of investigative groups assigned. The reports’ recommendations never mentioned looking at MLG cylinder overhaul processes. Considering the fact that these were two Title 14 Code of Federal Regulation (CFR) Part 121 aircraft, the reports barely registered on the major accident radar.

By comparison, the NTSB blue cover major accident report from December 18, 2003: AAR-05/01 (DCA04MA011), FedEx flight 647, an MD-10-10F, crashed in Memphis under similar circumstances, yet the report highlighted pilot error. However, FedEx 630’s accident report did refer to AAR-05/01, stating, “The fracture of the right main landing gear of this airplane [FedEx 647] initiated from the same air filler valve bore hole location as N391FE [FedEx 630]” A search of the NTSB.gov website’s Document Management System found no Maintenance or Structures Group factual reports in the dockets for any of the three accidents; these reports would have given the investigative groups’ individual factual findings. How, with almost identical events just three years later, was FedEx 630 not a major accident?

The second concern was the NTSB’s failure to look beyond the three FedEx accidents. How far did investigators go to prevent possible MLG cylinder failures in other MD-10 aircraft, e.g. Orbis Air’s MD-10? Did both a Maintenance investigator and a Structures investigator take their investigatory groups to examine the MLG overhaul process used by the FedEx contractor or interview the technicians performing the procedures? The DCA17MA022 factual report only spoke to Boeing’s DC-10 CMM revision and the ASB DC10-32A259, actions limited to the DC10 … and only the DC10. Did investigators give serious consideration that similar MLG failures could occur on other airliners, e.g. B777, A300 or MD-11?

Both FedEx 630 and FedEx 910 had resulting fires; both accident aircraft’s cabin areas were engulfed in flames and emergency exits were blocked by the fire. If either aircraft was a passenger airliner, a high fatality rate would have resulted. It is likely that all MLG overhaul facilities used similar plating procedures with similar results when overhauling wide-body MLG for passenger airliners. This suggests that a similar incident would have destroyed a passenger airliner with catastrophic results. Why were the two accidents not major accident investigation reports and why focus just on the MD-10’s MLG?

In 2006, FedEx 630, should have had a qualified Maintenance Investigator, with both air carrier and repair station experience; he/she should have led an investigatory group to explore the MLG’s overhaul facility to determine what issues – at the overhaul facility – if any, may have affected safety at the time, e.g. labor issues, quality control issues, management issues. In the wake of FedEx 910, both Structures and Maintenance Investigation groups, again, with experienced investigators with Title 14 CFR Part 121 and Part 145 backgrounds, should have conducted onsite inspections of the MLG overhaul facility.

Instead, the investigation mischaracterized information, e.g. the overhaul requirements. DCA17MA022’s factual report stated, the “manufacturer-recommended overhaul limit for the MLG assembly is every 8 years or 7500 flight cycles, whichever occurs first. At the time of the accident, FedEx’s MLG overhaul limit was 9 years or 30,000 flight hours, whichever occurred first.” Flight hours and flight cycles are not comparable. In reference to a landing gear component’s airworthiness, flight cycles are relevant; the landing gear is employed every single flight cycle. The landing gear is not used every flight hour, so flight hours do not affect landing gear integrity. FedEx probably received a time exemption from Boeing. Any cargo airliner’s years-to-cycles ratio is less than a passenger airliner’s; passenger airliners average more flight cycles per year. An air carrier-experienced maintenance investigator would have caught that.

Lessons Unlearned? One airline lost three of the same model aircraft to the same contributing factor. It is disturbing that two of these accident investigations were treated as inconsequential and ended up in a field accident report format. It is more troubling, however, that the investigations were treated as less-than-important as a passenger airline accident when one considers that information found in cargo airline accidents is critical to the safety of passenger airlines and the travelling public.