Posts about: "SAIB NM-18-33" [Posts: 31 Page: 2 of 2]¶

If I understand this correctly--

I believe the *inspection* was not conducted, and whether there was a fault with the configuration of the switch on the accident aircraft is not answered in the report.

If pilots were able to move this aircraft's cutoff toggles without lifting them, it seems that might have been reported at some point during its service. But then again, maybe the difference in operation between a correctly configured switch (requires lift to toggle) and incorrectly configured one (does not require lift, but lifting it still works as expected) is not noticeable.

I'd be curious to know if India Air has (finally) inspected these switches in their fleet since the accident.

The fact that SAIB: NM-18-33 was specifically mentioned, and that Air India's failure to inspect this airframe re the advisory was specifically mentioned, and that the exchange between the pilots specifically included wtte "I didn't", suggests to me that the report would like to hint at maintenance / build problems rather than deliberate pilot action.

that would surely involve a safety directive at this stage though?

I had posted before (and it had been deleted for some reason) that is appears as if air india is taking a substantial hit on their widebody capacity at the moment and keeps cancelling routes right now (the latest being LGW), could they be doing specific extra maintenance/ checks having more insight than almost any other stakeholders at this point?

Didn\x92t have to be but every mechanic would have simply wiggled the switch.
The throttle quadrant was also replaced.

Thats twice after the 2018 Boeing Service Bulletin so it\x92s not even applicable anymore.

Reading SAIB NM-18-33
My Interpretation/reading:
Some 737 Operators reported incorrect/broken locking features on cutoff switches - PN 766AT613-3D
If you have PN 766AT61 3 -3D installed - Replace it with 766AT61 4 -3D, which includes an improved locking feature.
The other Aircraft listed - have switches with similar design. In the case of the B787, switch PN 4TL837-3D. Check those AC to ensure locking is OK, and if you do happen to find something odd, let us (the FAA) know.
No-one, has ever found anything wrong with any of those other switches, or there would be AD's.
Thus there is not a problem with 787 Fuel Switch locking features.

So why did they give so much space to a discussion of SAIB NM-18-33? It's obvious that the switches were not faulty, or they'd have said. If they couldn't tell if the switches were faulty, they'd have said. They do tell us that the throttle control module was swapped out and there's been no problem with the switches. So they don't need to mention it. It doesn't read to me as a logical part of the preliminary report, but as something they were under pressure to include to imply that there may have been a technical problem rather than pilot malfunction.

The fuel control switches are clearly central to the investigation as the cause of the accident, and it is public knowledge that there was a SAIB relating.

Simplest answer is often the best - they included it to show they had considered it?

Imagine this forum if they hadn't included a nod to the SAIB - 90% of posts would be about the SAIB. can't really win on this one in the court of public opinion.

Included or not, they made no recommendations for even proactive reminding of the SAIB to operators. This is more telling for me.

It also is both possible without imagining things, and consistent with - shall we call it "best practices" under Annex 13 - for the person or persons who wrote and approved the preliminary report to have taken into consideration the attention their report would receive from many audiences, not only aviation professionals.

The prevalence of the 787 type. The quite recent travails of Boeing and the pace of its recovery (and some doubters that it can or will recover). The orders of magnitude increase in information, as well as misinformation or even disinformation, about this accident compared to .... well, compared to the UPS accident in Birmingham in 2013 (Flight 1354), cited as it was the first "current" accident occuring as of my stumbling across this forum and its threads. Sure, not a dramatic passenger aircraft accident but still valid for comparing the information environment then, and now.

The persons responsible for this report, I think, did not act improperly if they included information not strictly necessary for the purpose of keeping aviation cognescenti updated about what is known with some (imprecisely defined) level of certainty and clarity. Such other information items could be intended to make some effort at mitigating ("minimizing" would be hoping for too much) the volumes of noise emanating from all over.

Then there's the point about the report source knowing who did what, and when, but not providing specifics. Perhaps forensic analysis of the voice recording is ongoing, perhaps an analysis was completed but with reason to examine more closely. Regardless, I do not find it an affront either to solid, long-established principles of the Chicago Convention and Annex 13, or to the general ideas about advancing aviation safety, for the report sources to not treat the 30-day rule for preliminary reports as some "complete download demand function." Given what is reported about the fuel cutoff switches moving and the summarized cockpit statements, either way the final facts resolve will be tremendously impactful for the airline, the CAA of India, and the country (including but not only in its role as a major aviation Member State).

I wouldn't hold this view if it was a question of deception. I see it instead as a matter of reasonable discretion, about both ..."what to leave in, what to leave out" (with apologies to Bob Seeger, "Against the Wind", 1980).

The issue received extensive news coverage. I am sure they felt a need to address it.

Previously, I posted the content of a Reuters article about FAA (as well as Boeing) having issued notices to operators prompted by the reference in the AAIB Prelim Rpt w/r/t the SAIB about fuel switches in certain 737 aircraft (Special Airworthiness Information Bulletin No. NM-18-33, December 17, 2018).

Through a LinkedIn timeline I happened to discover the actual document the Reuters report was based on. It is entitled "Continued Airworthiness Notification to the International Community", issued by the FAA Aircraft Certification Service, Compliance and Airworthiness Division, dated July 11, 2025. As reported by Reuters, the FAA Notification document specifically references the fact that the AAIB Prelim Rpt made reference to the 2018 SAIB w/r/t the fuel switches.

The social media platform makes it difficult to transfer content off of it. Interested people may access the document in a LinkedIn post by former NTSB Chair Robert L. Sumwalt, NTSB Chair 2017-2014. (A search of the thread did not turn up the document; apologies if it's already here and I slipped up and missed it.)

If the detent is misaligned/damaged enough the upper stable position may not be fully reachable and the switch might instead rest in a pseudo stable position prone to collapse due to vibration or other outside forces.

> The FAA issued Special Airworthiness Information Bulletin (SAIB) No. NM-18-33 on December 17, 2018, regarding the potential disengagement of the fuel control switch locking feature. [...] Both fuel control switch were found in the \x93RUN\x94 position.

So correction first: It wasn't an Airworthiness Directive, it was just an SAIB, but also the above is the only information provided by the preliminary report. Notably they did not comment in any way on the state of the guard/detent.
I'd not dismiss this event so out of hand. After the 171 crash every single pilot flying for Air India surely has heard that those switches are blamed, right? For any of them to be willing to faff around with those seems alarming and, for me at least, points to possible normalization of deviance. It may be practice for them to not treat these switches as a potential flight safety issue.