There are a number of similarities between the grounding of the DC-10 back in 1979 and that of the Boeing 737 MAX more recently. The DC-10 recovered from its issues, so why does everyone think it will be more difficult to return the 737 MAX to service? Simple Flying investigates.
The last time the FAA ordered a temporary grounding of a particular aircraft model due to a fatal accident was back in 1979 when the McDonnell Douglas DC-10 was grounded for two months. Although some passengers alluded to the DC-10 being a ‘jinxed’ aircraft, the majority still happily flew on it for many years, and even today it’s in use, often as the MD-11, for freight operations around the world.
So, if the DC-10 recovered from its grounding successfully, why shouldn’t the 737 MAX too?
What happened to the DC-10?
On May 25th, 1979, 257 passengers and 13 crew boarded a DC-10, tail number N110AA, bound for Los Angeles from Chicago. The passengers of American Airlines flight 191 were no doubt looking forward to the trip, on the comfortable triple engined, twin-aisle McDonnell Douglas aircraft, known as one of the best ways to get around the world in that era.
However, as the plane took off from O’Hare, ground observers noticed something strange was going on. The aircraft had keeled over onto its left side, to the point where it was almost flying in an inverted position. Moments later, the aircraft erupted into a huge fireball, taking the lives of all 271 people on board, as well as two on the ground.
A keen eyed American Airlines employee who was watching from the ground saw everything unfold. The engine under the left wing had detached from its pylon, flying up and over the wing. Its path over the wing damaged the hydraulic fluid lines that keep the wing’s leading edge slats in place, causing the aerodynamic characteristics of the wing to fail.
How did this happen?
The ensuing investigation traced the issue back to a maintenance inspection which had taken place a couple of months previously. At a facility in Tulsa, Oklahoma, the DC-10’s engine had been removed from the wing, for work to take place.
According to McDonnell Douglas’s procedures, the engine should have been unmounted from the pylon before detaching the pylon from the wing. However, some carriers opted to remove the engine and pylon as a single unit, in a bid to save man-hours during the maintenance process.
Doing it this way relied on a forklift operator being precisely positioned so as not to cause damage to the pylon assembly. With the forklift driver unable to even see the pylon and wing, this was a recipe for disaster. It appears that, in the case of N110AA, they got it wrong and caused unseen damage to the attachment points of the pylon.
The aircraft continued to fly for around eight weeks, with the weakness in the assembly getting worse with every flight. Eventually, it failed, causing the worst disaster in US aviation in history.
The DC-10s grounding
DC-10s around the US were inspected, and several at American Airlines and Continental were found to exhibit the fault. Two weeks after the crash, the FAA grounded all DC-10s in its jurisdiction and introduced a regulation banning foreign DC-10s from US airspace. The type certificate was restored in July 1979 and the regulation repealed, allowing the DC-10 to fly again.
Prior to the American Airlines accident, the DC-10 had been involved in two other incidents. American Airlines flight 96 had a cargo door blow out, leading to a very narrow escape thanks to the skills of the pilots in making an emergency landing at Detroit. Again, in 1974, a cargo door blew out of a Turkish Airlines flight, leading to the plane crashing in a French forest and all 346 onboard losing their lives.
But, even after the grounding, the DC-10 continued to have issues. A Western Airlines flight crashed in Mexico City in October 1979, and a month later an Air New Zealand service flew into a mountain, killing all 257 on onboard. Ten years after this, United Airlines flight 232 crash-landed in Iowa, killing 111 of the 296 people on board.
Despite this, the DC-10 remained a popular aircraft for both passenger and cargo operations. It was only in 2014 that Biman Bangladesh flew the very last DC-10 passenger flight, and some DC-10s are still in operation as cargo aircraft today. Clearly, the DC-10 recovered from its grounding, so can we expect the same from the 737 MAX?
The similarities and differences with the 737 MAX
The 737 MAX was grounded following two fatal accidents. When the FAA ordered the grounding of the type, it was only the third time in history that the Administration has done such a thing – the first being in relation to the DC-10 and the second time the 787 Dreamliner (which had not caused any fatalities). Despite its checkered past (and future issues), the DC-10 lived on… so how did it get over its grounding?
There are some lessons from the DC-10 which are or could be applicable to the 737 MAX. For example:
- Rebranding: The DC-10 was, post-merger, quickly rebranded to the MD-11, which may have saved its reputation for being a dangerous plane. The 737 has already been mooted for a rebrand; could it have the same effect? (note: the MD-11 was not just a new name, but also a new plane. Various design modifications came with the rebranding, something that is not on the cards for the 737 MAX).
- Operators were on board: Despite the crashes, operators continued buying the DC-10 and flying it all over the world. The 737 MAX has also had its fair share of post-crash orders, showing that at least some operators still have confidence in the craft.
- Investigations were thorough: The DC-10 was gone through with a fine-toothed comb to ensure its safety. The MAX is having the same treatment. Once approved, it should, in theory, be one of the safest aircraft to fly in.
However, there are some stark differences between the two situations also, which make the situation for the 737 MAX somewhat more difficult to recover from. For example:
- It’s a design problem: The DC-10 issue was found to be the fault of the operators, not following maintenance procedures correctly. Conversely, the issue with the MAX lies with the design and manufacture of the aircraft.
- It’s a global issue: The malfunction of the MCAS can affect every MAX in the world. The DC-10 problem was limited to those operators who had ‘streamlined’ the maintenance process.
- The grounding is global: The DC-10 was grounded by the FAA only. The MAX has been grounded by every aviation regulator in the world and will require the approval of every regulator to get it back in operation.
- Social media is a thing: People are so much more connected these days, and more aware of big issues like this. Although some thought the DC-10 was a ‘jinxed’ aircraft, it’s likely that not many outside of the US were particularly aware of the issues. Added to this, once it got rebranded many wouldn’t have realized it was the same plane, albeit with some improvements. With social media as it is today, we all know which airlines are trying to hide their MAX behind another name.
- Re-engineering won’t work: The whole problem of the MAX comes down to trying to place larger engines on an old airframe. This made it lose aerodynamic stability, leading to the introduction of (faulty) software to correct the problem. When the DC-10 became the MD-11, it was fundamentally redesigned to make it better. The 737, although much loved and very successful, has reached the end of the line in terms of updating. Any further redesign will require a completely new airframe.
- The grounding is dragging on: The DC-10 was, relatively quickly, inspected and returned to service with a clean bill of health. The issue was clearly identifiable, easily rectified and not a fundamental flaw with the plane. The MAX, on the other hand, is the polar opposite. The longer the grounding goes on, the more flaws are found with the plane. Its return to service is getting pushed further and further back, with passenger confidence diminishing every step of the way.
While the 737 MAX no doubt will return to service eventually, both Boeing and the operators of the type are going to have to work very hard to restore consumer confidence. While there are some parallels to be drawn between the DC-10 and the MAX, the differences in the two situations are what will make a successful return much harder for Boeing’s best-selling jet.