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Maintenance Induced Failures

One should be glad to have folks like Mike Busch, that question conventional wisdom, rock the boat, inflict a little bit of controversy, and foster quality discussions

Well, his articles are good, condensed and to the point. Still I have seen nothing there that haven’t already been discussed at length at VansAirforce In the experimental (and ultralight) world, we have a slightly different approach to “conventional wisdom” than the “spam can flying” certified crowd

To the article. It states that in GA 75% of accidents are pilot induced, 13% are design induced and 12% are maintenance induced. One of the basic philosophies of RCM is the 20/80 rule. Find the 20% of faults that causes 80% of the problems, then fix those 20% and forget the rest (very simplified, but essentially correct). RCM does not discriminate between faults, if they are operator errors, fatigue, wear, lightning, war or whatever.

By applying RCM philosophy on GA we end up with the all too obvious conclusion that 75% of the faults are caused, not by 20% of factors, but one single element; the operator, the pilot (maintenance personnel are not operators). So, according to RCM we should “fix” the pilot and forget about the rest (common sense really). Consequently GA maintenance is not something we should focus our attention to, there is nothing “wrong” with how things are done today, because it is irrelevant – according to RCM philosophy. Just to make a point here.

Anyway, instead of all the talk, I really would like to see him do a RCM analysis on the engine, just a simple pen and paper approach would do just fine. With RCM as with any other philosophy, you will eventually end up with the problem of deciding how to best handle hidden critical failure modes in some components. Failure modes that are not detectable by an operator (again – the pilot, not maintenance personnel), and have fatal outcome for the basic functionality of the engine.

The elephant is the circulation
ENVA ENOP ENMO, Norway

One has to consider that Mike Busch et al. not only are very knowledgeable engineers, they also happen to be very clever businessmen.

What’s wrong with that? I found Mike Busch webinars very well done. He backs up his arguments with data, and good research, and articulates his thoughts extremely well. There is no evidence of collusion. One should be glad to have folks like Mike Busch, that question conventional wisdom, rock the boat, inflict a little bit of controversy, and foster quality discussions. For example, the Engine Monitor manufacturers could have easily implemented Failing Exhaust Valve Analytics into their engine monitors, and build a public engine data analysis web site. They didn’t.

United States

It is very true that Busch and Deakin are doing advertising all the time, but they also happen to be right most of the time IMHO. I think these guys have done GA a massive favour, educating a generation of pilots on correct engine management, in the face of Lyco/Conti lawyers banning any change to their manuals because any change would be suggestive of past instructions being incorrect. Plus many pilots don’t have the instrumentation to do it right.

Advertising happens everywhere, online. Not always as openly. Just look at how certain posters appear on pilot forums when they launch a new product or a service The smarter ones will actually participate in the forum generally and usefully (which happens to be the EuroGA requirement, though it is obviously difficult to enforce). The others throw in a few one-liners to make it look like they are. The dumb ones just post about their product… and hope to get exposure before the posts are deleted. Recently one UK insurance broker has got half his office to post questions on the UK aviation “chat sites” which he then answers… a bit obvious when the “half of his office” then reveal their identity on another site…

It happens in the US forums too, but the commercial posters tend to be very open about it (e.g. Garmin reply to questions (well most of them) which they would never do in Europe) and I am sure they get a lot of business out of it because they do detailed helpful posts.

I’ve been approached by many people re advertising on my peter2000.co.uk site but have always refused (it now costs me only $20/month for the hosting) because it would undermine its value, not to mention put people off.

It’s a tricky subject.

BTW one cannot compare car engines with aircraft engines, because a car engine spends most of its time at 10-20% of max rated power. If you ran an IO540 at 10-20% of max rated power, it would have a 1000000hr TBO In fact it may not even need any airflow on it…

I agree that distraction is the number one cause of maintenance errors, the usual reason for this slipping past the quality system is that the old fashioned chief engineer who once stalked the hangar floor keeping a watchful eye on the work is now confined to the office doing EASA paperwork.

Can this be streamlined?

In electronics, ISO9000 has created a lot of paperwork but you get a consultant in, throw a few k at him, he generates a load of forms and a “quality manual” (which is full of crap and platitudes) and you just run the charade. If your products were crap before, they continue to be crap.

Most paperwork systems can be automated to various degrees. I am surprised there aren’t off the shelf packages for this. In the bizjet world, you have tracking systems for maintenance. It’s all computerised. They run rolling maintenance (no Annuals) and all the parts are tracked and done when their time comes up. Actually I vaguely recall the systems are all online i.e. no need to buy the ATP CD MMs for every type you work on (which many firms don’t actually have, even though one (IMHO overly restrictive) interpretation of Part M is that they must subscribe to every one).

I used to use a Part M shop for my TB20 annuals (they had an A&P/IA on staff) and they had a highly automated paperwork generation system. Just a few clicks and a 100 page report popped out of the laser printer. Full of crap and platitudes but … I left that firm when they demanded I sign a contract under which they are not liable for any damage unless “by a willful act of their staff”.

Let’s face it… every release to service I have ever seen states “IAW the manufacturer’s MM”, but not a single annual was actually done IAW the mfg MM. For example, on a TB20, the MM has about 100 pages of items to do. Most are inspections only, but there are lubrication tasks which cannot be performed (unless you are cynical enough in English language interpretation to write the Yes Minister script) without dismantling items which not a single outfit I have ever come across will do. Well, some will do them, but only if you pay for it separately – say £500.

Last Edited by Peter at 02 Aug 16:28
Administrator
Shoreham EGKA, United Kingdom

But TBR and TBO are not black and white, there are shades of gray. If you wanted TBR, then you had to throw away the whole airplane after the engine reached 1200 hours (or whatever).

Yes, and that’s pretty much the way my Japanese car is owned and operated. It’s not done based on hours but frequency of failure, but otherwise as the first owner you expect very limited repairs and no overhauls during a long period of ownership. Then if you’re like me you will have run it a great many miles/km and you’ll sell it for maybe 20% of its original price.

That philosophy requires a very high volume product, with a huge budget for engineering out all the variations in MTBF between components. And even with that, it’s expensive. For a light aircraft sold in limited volume that product philosophy would be a financial disaster.

As the saying goes, be careful what you ask for, you might just get it.

Commenting on Mike Busch’s article directly, I think most of it is common sense. There’s a balance between under attention and over attention when it comes to fiddling with planes. One factor he doesn’t mention in this article though is that if the pilot is involved and learns how the thing works, the education enhances in flight decision making and increases flight safety.

PS I actually don’t drive one of these, because cars are not aircraft or vice versa, but its a great temptation to say I do…

79 Ford Falcon

Last Edited by Silvaire at 02 Aug 14:49

Yes, even a brand new engine has to installed….we are talking mainly about human factors here. Not the inherent reliability of a piece of machinery….even a brand new engine has a “bathtub” reliability curve

YPJT, United Arab Emirates

There are virtually no maintenance induced accidents in European GA.

Granted this is not Europe but Switzerland (but HB-PRE had been D-EHKM until less than a year before the accident), but the accident report of HB-PRE raises some serious questions about the maintenance (even though the actions of the pilot weren’t – um – overly clever)

Yes, and the logical extension of this is TBR, not TBO.

But TBR and TBO are not black and white, there are shades of gray. If you wanted TBR, then you had to throw away the whole airplane after the engine reached 1200 hours (or whatever).

Even for a Lycontinental, there are items that must be replaced mandatorily every time the engine is taken apart. And the better European overhaul shops throw away rather more than absolutely required by the engine manufacturer.

LSZK, Switzerland

Good point!

EBZH Kiewit, Belgium

One has to consider that Mike Busch et al. not only are very knowldgeable engineers, they also happen to be very clever businessmen. Their articles, columns, webinars are all part of their business. Talk bad about the standards of maintenance = sell more seminar seats. Become famous doing so = be invited (for big $$) to speak at aviation conventions. Pledge for and against certain products = partner up with certain manufacturers = more $$.

American style marketing is more direct and blunt than marketing in Europe.

Last Edited by boscomantico at 02 Aug 12:01
Mainz (EDFZ) & Egelsbach (EDFE), Germany

One of the major findings of RCM researchers was that preventive maintenance often does more harm than good, and that safety and reliability can often be improved dramatically by reducing the amount of PM and using minimally invasive techniques.

Yes, and the logical extension of this is TBR, not TBO. When a piece of machinery has run for a certain amount of time, or starts breaking, it is considered trash. Repair or overhaul is a waste of time and money. Things are manufactured in very strict condition, the less hands that touch the stuff, the better. A lycoming is not designed nor manufactured around these more “modern” principles. But, there is nothing inherently wrong with “hand made” stuff that is meant to last “forever” either. It only requires more attention to detail and more dedication (in production and repair) and ends up costing 2-1000 times more than an equal quality “wasteable” unit depending on complexity and units produced.

There are no holy grail with these things, for the same reason that doing EASA paperwork around fancy maintenance routines is no replacement for a second pair of watchful eyes on the hangar floor. I remember learning about RCM ages ago. Today RCM means (if it is still called RCM that is) choosing the maintenance strategies (often several and on several levels) that ultimately minimizes a set of constraints, be it cost or risk or safety or whatever, in any combination. But RCM is certainly no excuse for sloppy maintenance, and an RCM analysis may very well result in scheduled maintenance being the best option.

A Lycoming is an old fashioned “hand made” piece of machinery. I would believe it works best if i is treated as such, but it must be treated properly. A BMW engine that is made to run for 200, 300, 500k? km without a single incident of any kind, and then thrown away is not even remotely related to a Lycoming engine.

As I am building my own experimental engine, from scratch, I also have to have some maintenance strategy. There is no TBO, not even “suggested” for homebuilt experimental engines. I have read several pieces of Mike Bush. They are interesting, but he is ultimately only pointing fingers at all and everything he feel is wrong, and this isn’t very helpful. With his experience and competence he could easily do a proper and thorough engineering RCM analysis that would serve as an example of an alternative (but practical) way to maintain aircraft engines (old “had made” ones).

The elephant is the circulation
ENVA ENOP ENMO, Norway

There are virtually no maintenance induced accidents in European GA. Therefore I do not believe that there is a problem.

Only because one can deal with a frozen elevator trim in flight – caused by some idiot spraying some no-name motorbike lube in there.

If the resulting autopilot failure happened in IMC and at a bad moment, it might have been more interesting

It is difficult to make a fixed wing plane crash via bad maintenance but one gets close fairly often IME.

Last Edited by Peter at 02 Aug 11:39
Administrator
Shoreham EGKA, United Kingdom
17 Posts
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