Lion Air Finds Cracks On Younger Boeing 737s

Indonesian airline Lion Air has found structural cracks in two of its Boeing 737 aircraft. Other airlines have found the same problem in recent weeks, but the Lion Air aircraft in question have flown fewer cycles than the FAA threshold for safety checks.

Lion Air Boeing 737
Lion Air have found pickle fork cracks in two of their Boeing 737 NG aircraft. Photo: PK-REN via Flickr

Budget airline Lion Air has grounded two of its Boeing 737 NG aircraft after finding cracks. This makes it the latest airline to ground the 737 with the same problem. The cracks are located in an area known as “pickle forks”, which help reinforce the connections between the main body of the aircraft and the wings.

An ongoing problem

Lion Air is not the only airline to have found this issue. Qantas also found similar damage on three of its 737 NG aircraft last week.


After initial cracks were found in October, the FAA issued an order which required all 737 NGs that had flown more than 30,000 cycles to be inspected within seven days. In addition to this, all planes with more than 22,600 flights had to be checked within the next 1,000 cycles.


Qantas hurried to comply with this directive after it discovered a crack during routine maintenance. It has now grounded three aircraft with damage but has not grounded its entire fleet of 737s. The Sydney Morning Herald is reporting that “Qantas has inspected 33 aircraft above 22,600 flight cycles, leaving 42 which have not been inspected.”

“Even where these hairline cracks are present they’re not an immediate risk, which is clear from the fact the checks were not required for at least seven months,” said Qantas domestic chief executive Andrew David amid calls to ground all 737s.

Quantas Boeing 737 Aircraft
Qantas are facing fresh calls to inspect all 737 aircraft after finding three damaged planes. Photo: Hugh Llewelyn via Flickr

Cause for concern

The two damaged Lion Air aircraft have sparked fresh calls for concern as they have each flown fewer than 22,000 flights. This is below the threshold for mandatory checks and the cracks were only discovered after Lion Air performed their own checks to “ensure security and safety of the flights”.

A spokesman for Lion Air confirmed that the aircraft are now grounded until further checks and repairs have been carried out.

Lion Air 737
The affected aircraft will be grounded until repaired. Photo: Afrogindahood via Wikimedia

As the Lion Air aircraft were found to be damaged despite having flown less than the 22,600 cycles, the FAA may now decide to issue an order for operators to inspect all 737 NG aircraft.

An FAA spokesperson said the agency had asked airlines to report any further damage found. This is so it can make a full assessment of the situation and potentially change its inspection policy.

Fewer than 5% have had an issue

Lion Air is yet to issue a statement. However, Indonesia’s Director-General of Civil Aviation, Polana Pramesti, said the country’s aviation regulator was going to follow the FAA directive. He said that, at this time, there were no plans for further mandatory checks.

While Boeing did not respond to Simple Flying’s request for a comment, it has previously stated that approximately 1,000 aircraft worldwide had met the FAA threshold for checks. Of those which had been checked, fewer than 5% had any issues.

No doubt Boeing will be anxious to ensure any further damage is dealt with as quickly and quietly as possible as it continues to deal with the aftermath of the two 737-MAX crashes. Do you think Boeing’s reputation could handle another scandal involving aircraft safety? Are the pickle fork cracks serious cause for concern for the company? Let us know what you think below.


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In-Frequent Flyer

Given Lion Air’s reputation, I wouldn’t be surprised to find maintenance issues given how they handle their planes….


The pickle forks can’t be influenced by an airline’s maintenance procedures: they’re not a part of the structure that should ever have to be seen, cleaned or serviced in any way. This is purely a failing by the airframe manufacturer.
An analogy might be the foundation of a house: the house owner is justified in assuming that it will last a lifetime, and he shouldn’t have to clean or service it in any way to achieve that. If he discovers cracks in it, he can point a finger at the builder/architect.


Agreed Peter ! This pickle fork cracking issue has nothing to do with the carrier or maintenance. Pickle forks were designed to last over 90,000 flight cycles. This premature cracking indicates the supplier is at fault. Maybe the supplier did not maganflux the pickle forks or they used substandard alloy / heat treatment ? Definitely not Lion’s fault, as they proactively looked for the cracks way before they needed to. Boeing will have to pay dearly for this mess.


Ahhhhhhh, wellllll – yes, I agree with you on the pickle forks and life of the aircraft thing…having just dug up around the foundation of my house to repair cracks, leads me to believe that concrete does not last as long as aircraft!!! Mind you, I’m not sure I could come up with a better analogy then you have, Peter – just don’t talk to me about land shifting/settling, foundations & footings, membrane installation, french drains and water infiltration. Arrrrgh!


Sorry to hear about your foundation 🙁
If you live in an area with ground subsidence, the engineer/architect should have driven piles into the ground before pouring the foundation.


This pickle fork issue is starting to take on sinister proportions.
I wouldn’t be surprised if we quickly see this leading to a more extensive airworthiness directive (at least), or even a possible global grounding (hopefully short-lived, but who knows?).
Interesting that the latest issue (< 22000 cycles) was discovered pro-actively by LionAir; maybe people will now lay off a bit with the accusations that LionAir doesn't take safety seriously.


Scary isn’t it that Boeing has been using the 60 year old airframe design by adding larger and more powerful engines and finding out premature wear on not only the pickle forks, but other structures too. Boeing being the lazy idiot run by bean counters, failed to design new airplane types that would be better suited for these newer engines – case in point: MAX. Boeing keeps using the same old airframe but changing out the engines to make it easy to type certify. This was how the MAX had a band aid software put on to counteract the high… Read more »


That’s a good point, Pats. Are the current pickle forks the same as the ones designed for the 737 Classic’s? Anyone hear anything?


I think I read somewhere (Leeham?) that they are…not sure. It’s a very urgent question!
Importantly: were the same pickle forks also used on the MAX? If they were, they’ll probably fail even faster (heavier engines).


Just found the article on Leeham (see below). It asserts:
“The affected 737 types are NG only; the MAX and Classic have a different wing attachment design. The P-8 Poseidon, a derivative of the NG, also is unaffected.”

Greg Hiller

Yes, and still not ‘fly by wire,’ as are all other current airliners, and have been for many decennia: You couldn’t make it up.


Indeed. And the re-engined 767 that Boeing is touting as a possible NMA replacement probably also won’t get a fly-by-wire architecture. It’s like using steam locomotives in the 21st century.


Now I await with interest the first of the B787 problems (not engine related) start to surface.


Well, apart from the manufacturing quality issues in Charleston and the recent allegations about defective oxygen bottles, a new potential issue was reported on Flight Global this morning:

(second half of report…first half is about a new issue in the MAX)


Air Canada got a 787 with a leaking fuel tank


Thanks for that Peter


Hmm, the battery? Remember when it got grounded for 4 months. All they actually do is to put harder cover around the battery. Not replacing it.


If they found cracks below the 22,600 limit, then its a serious crisis – for the Indonesian authorities failing to act immediately and order 15,000 and over inspections is nuts.

FAA and EASA should be mandating immediate checks for 15k and checks for all withing a month, sooner if more cracks are found lower.

It does not matter if they are flyable, its how far down the issue goes and what the base cause is.


I find it intriguing that the pickle fork problem occurred on an Indonesian Aircraft. Most Indonesian runways are high quality flat and smooth. This contrasts with older runways in places such as Darwin haven’t had much change bar a new layer of tar since WW2. It’s got three distinct bumps or tiers which can be easily seen from Amy Johnson Ave that force extra pressure on the wings when landing as you have to put the plane down hard.
Unless a parallel runway is built, this will never be fixed.


Why are you assuming that the pickle fork problem has anything to do with the runway?
The wings experience substantial mechanical stresses during flight, and these stresses are transferred to the fuselage via the pickle fork. If the wings flex enough during flight (e.g. as a result of frequent turbulence), then the pickle fork suffers. But it should be able to withstand such suffering for decades…and, instead, it’s failing after just a fraction of that time.


Since the pickel fork is not easily serviceable, I wonder what will happen to those aircraft that has cracks? Will boeing repair/replace them for free or airlines scrap the aircraft entirely?


The plane doesn’t have to be scrapped. The pickle forks can be replaced, at a price of $250,000 per plane! I presume/hope the airlines in question will send the bill to Boeing.