Military study regarding increased squawks after maintenance

jetrep

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jetrep
Years ago I came across a document (most likely a PDF) someone linked to on a message board. It was a study that I recall being performed by the military showing that equipment ended up with additional squawks after maintenance was performed.

I found it interesting and have been trying to find it without success. Is anybody familiar with this?
 
Where do you think the phrase "don't fix it if it ain't broke" came from?
 
I think Manifesto (Busch) discussed it but don't recall a reference given in the book
 
Had a 727-100 come out of "C" check from a prominent US vendor with a serious aircraft pitch discrepancy. Found the horizontal stabilizer jackscrew "X" dimension ( zero degree pos.) to be set for -200 specs. That put the -100 at an abnormally nose high attitude in the stabilizer takeoff/landing band range.
 
So if you perform maintenance on one squawk then you get another squawk due to the maintenance, are you saying you should not have performed maintenance on the first squawk? So then do you perform maintenance on the second squawk or do you not so as to avoid a third squawk? I guess the lesson is to just leave the first squawk alone so as not to create the cascade effect of multiple squawks.
 
The British military did a study during WWII about maintenance induced failures, known as the "Waddington Effect"
 
named after Conrad Waddington from the Coastal Air Command.
 
Mike did a seminar called Maintenance Induced Failures.
http://www.eaavideo.org/video.aspx?v=2016238711001
Describes Waddington's work.
Some good examples around minute 20.
The graphs of engine failures versus hours show most occur in the first 100 hours or so then goes way down to over 2000 and there isn't enough accurate data after that.

SO important to treat the first few hours after maintenance VERY carefully.
 
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Years ago I came across a document (most likely a PDF) someone linked to on a message board. It was a study that I recall being performed by the military showing that equipment ended up with additional squawks after maintenance was performed.

I found it interesting and have been trying to find it without success. Is anybody familiar with this?


Not familiar, but don't doubt it. I am based at and live next door to an airport where much maintenance is done on business jets. The number of planes I hear on my scanner that request a return to maintenance before even reaching the runway is amazing.
 
So if you perform maintenance on one squawk then you get another squawk due to the maintenance, are you saying you should not have performed maintenance on the first squawk? So then do you perform maintenance on the second squawk or do you not so as to avoid a third squawk? I guess the lesson is to just leave the first squawk alone so as not to create the cascade effect of multiple squawks.
No, but sometimes (military in particular) has a bad habit of tearing stuff apart and re-assembling it based on an arbitrary time or calendar limit. And that often creates more problems than it solves.
 
So if you perform maintenance on one squawk then you get another squawk due to the maintenance, are you saying you should not have performed maintenance on the first squawk? So then do you perform maintenance on the second squawk or do you not so as to avoid a third squawk? I guess the lesson is to just leave the first squawk alone so as not to create the cascade effect of multiple squawks.

Yeah. Don't do any inspections of any sort. No preventive maintenance. No oil changes or plug cleaning. Nothing. That will make everything the safest possible.

Really, folks. Anything that involves humans has the potential for error, and errors and oversights are bound to creep in. The trick is to minimize those, and it costs money to do that. Training, resources, double-checking stuff, lots of things, and all of them add to the cost of the maintenance. Owners don't want the costs going up, so many of them pick the cheapest shops and are then annoyed with the mistakes.

dirty-dozen-human-factors.gif
 
This is not restricted to aviation. The USN ship I was assigned to went into the Charleston Navy Shipyard for a normal overhaul. The evaporator (used to make fresh water from salt) was basically circular in shape and it was installed back in its case upside down. Dock trials of the main throttle valve revealed it would open in the reverse direction and it could not be closed. When it was disassembled, it was discovered that the parts that needed to be refurbished by welding additional metal to them had not been done at all, and then the valve was re-assembled incorrectly and reinstalled. There were other problems as well.

Good thing the Shipyard was closed a few years later in an armed forces-wide reduction of staffing. We couldn't believe that these same geniuses work on nuclear powered submarines, too!:eek:
 
Good thing the Shipyard was closed a few years later in an armed forces-wide reduction of staffing. We couldn't believe that these same geniuses work on nuclear powered submarines, too!:eek:
Unfortunately, yard birds just moved to other shipyards, so I'm not so sure how much of a good thing it really was.

As a former Navy Chief Engineer, I have waaaay too many similar stories myself.
 
Often, not always, would find new squawks on Functional Check Flights, after maintenance, where we exercised everything, just to see. . .also, we used to take our C-130s to a depot in Florida. They had a perfect record; not once in a decade did they have an airplane airworthy when it was "ready" for pickup. One time we gave up, flew one home, gear down, doors off, after a couple of days of attempts to correct an issue.
 
also, we used to take our C-130s to a depot in Florida. They had a perfect record; not once in a decade did they have an airplane airworthy when it was "ready" for pickup. One time we gave up, flew one home, gear down, doors off, after a couple of days of attempts to correct an issue.

Ongoing problem even now. Most depot folks are civilians who work for some flavor of L3, Dyncorp, etc. They are union labor, so if it isn't during their normal workday, or if it isn't specifically in the contract, it isn't happening. Every command I've been in has had jets on the books (like significant numbers) that were in depot for my entire 3 year tour and I never once saw them. I think this is the biggest factor in the recently heavily publicized aircraft shortages that all the services are reporting. We own the assets, but the ones we need on the front lines are in a decade long backlog at the depot because we can't un F our contracts or the money we are willing to pay them to do the work. But moving to a primarily contractor based work force has surely saved money in the bean counters minds in their holes in Washington.
 
The Waddington Effect. Brilliant! This is exactly what I was looking for. Thanks guys
 
Yeah. Don't do any inspections of any sort. No preventive maintenance. No oil changes or plug cleaning. Nothing. That will make everything the safest possible.

Nobody suggested this. Dumb insinuation.
 
I was an avionics tech for a major repair depot for a couple of years after getting out of the Navy. We did the heavy checks on 737 and MD80 for major carriers. You just can't appreciate the depth
of a "C" or "D" check unless you've seen the aircraft stripped down to bare metal and then put back together and repainted.

We'd strip the cockpits, all cabin interior furnishings, and avionics bays bare. so the airframers could do their inspections and repairs, then we'd put it all back together and ramp check every thing. We'd do extensive function checks on everything, then go on the test flights. I always thought it was amazing that there weren't more gripes after major maintenance checks.

Had a 727-100 come out of "C" check from a prominent US vendor with a serious aircraft pitch discrepancy. Found the horizontal stabilizer jackscrew "X" dimension ( zero degree pos.) to be set for -200 specs. That put the -100 at an abnormally nose high attitude in the stabilizer takeoff/landing band range.

I don't doubt that happened. But, 727 HS jack screw rigging is one of those things that, for it to get out of depot and accepted by the customer, there were multiple folks on both sides of the aisle slipping.
 
Don't forget about the paperwork involved in overhauling and refueling a nuke. When I was a yardbird at MINSY back in the mid 1970s we said that an overhaul/refueling job on a submarine wasn't complete until the weight of the paper equaled the weight of the boat. And I'm sure it has only gotten worse. That was 40 years ago. I can only imagine what it's like today. Oh, and MINSY got shut down a number of years (decades?) ago, too.
 
Keep on mind, almost 50% of fatal aircraft accidents are pilot error, almost 5% are mechanical, or maintenance related.
True. However, is there statistical data breaking down the initial cause leading up to the 50% of pilot errors? As an example: a stalled airplane fatal crash after engine failure. It would be great to have insight into those.

A real world example from not so far past from my hometown: a newly-minted twin pilot was bringing his new twin home from an hour away. The pre-buy mechanic failed to tighten one of the turbocharger hose clamps and it got ingested and seized the #1 engine. THAT should count as maintenance-induced incident. However, it got filed under CFIT because the pilot forgot the basic rule of aviation (FTDA) and stalled her into ground on short final in VMC on a CAVU day. :(

And I agree with others that one needs to be very vigilant after maintenance. I have never had the luck of finding 0 problems after maintenance. Always something. May it be missing inspection covers, loose screws, missing screws, hoses not connected, wires hooked up incorrectly etc.
 
True. However, is there statistical data breaking down the initial cause leading up to the 50% of pilot errors? As an example: a stalled airplane fatal crash after engine failure. It would be great to have insight into those.
In my own analyses, I list the "Initiator" of the accident...the first major occurrence in the accident chain. So in the real-world case you described, my analysis would indicate an initiator of "Maintenance Error" and not the stall.

And, still, the rate of mechanical failure is much less than the pilot error rate. Pilot error runs roughly 45-60%, mechanical issues roughly 5-15% (depending on aircraft). This is obscured by the number of accidents due to engine failures where the cause cannot be determined. It might be pilot-related...failure to use carb heat, mishandling the fuel valves and starving the engine.... but it is still another 5-10% of the accidents.

Ron Wanttaja
 
I wonder if money is truly saved? Every contractor I have seen seems to charge an outrageous rate. I suspect these contracts are just political handouts. Doesn't mean the military can do it better or cheaper either. The whole DOD is just a bloated mess.


Ongoing problem even now. Most depot folks are civilians who work for some flavor of L3, Dyncorp, etc. They are union labor, so if it isn't during their normal workday, or if it isn't specifically in the contract, it isn't happening. Every command I've been in has had jets on the books (like significant numbers) that were in depot for my entire 3 year tour and I never once saw them. I think this is the biggest factor in the recently heavily publicized aircraft shortages that all the services are reporting. We own the assets, but the ones we need on the front lines are in a decade long backlog at the depot because we can't un F our contracts or the money we are willing to pay them to do the work. But moving to a primarily contractor based work force has surely saved money in the bean counters minds in their holes in Washington.
 
I wonder if money is truly saved? Every contractor I have seen seems to charge an outrageous rate. I suspect these contracts are just political handouts. Doesn't mean the military can do it better or cheaper either. The whole DOD is just a bloated mess.
Oh yeah, that was the case in the past, anyway. At one pint, USAF had to reduce the number of flying Wings, to pay to keep depots open to service aircraft they weren't flying anymore, because they stopped flying 'em to keep civilians employed at depots they didn't need. . .
 
I've found major aircraft issues coming out of an MX base. I was doing a walk around on one and found that part of the leading edge was missing and the landing light lens was sitting on top of the wing. The plane had been signed off as airworthy and towed to the gate.
 
I wonder if money is truly saved? Every contractor I have seen seems to charge an outrageous rate. I suspect these contracts are just political handouts. Doesn't mean the military can do it better or cheaper either. The whole DOD is just a bloated mess.

In my personal opinion, absolutely not. In many cases as well, the quality of the work very inferior to what it used to be when handled by active duty personnel. I'm not just talking maintenance, but also most customer service and support functions, really just about every area that could possibly have been pawned off on contracts. I know some great contractors, but many more cases, it is a crime they are getting a paycheck at all for what they do, let alone a paycheck that is 2-3 times what their military equivalent would be getting paid. I know there are some more in depth reasons why even in spite of this, money might be getting saved, but at the end of the day, the MISSION is not getting done. If you want to knock off government handout programs, start with military support contracts.
 
I'm a contractor and am currently making 10K LESS than I was as a uniform member doing the same thing managing a program of 1 Mil + and 90 Soldiers. Also, if I step out of line and do anything that is not outlined in my contract I will be fired such as taking part in christmas gift exchanges, BBQs, taking a class (even if it relates 100% to my position). Contractors can be cheaper even with a higher annual rate because the gov is not providing housing, meals, medical or pensions. This year marks the end of my contract. The last time a new contract was presented I took a MAJOR pay cut to keep my job. Now that I'm about 1/2 way back to my last wage, well..... we'll see.
 
I feel your pain brother. My response is really too heated to post on here. I'm sure you are one of the good ones, so I will leave it at that.
 
Former mech of mine worked military contract (UH-60) for all of about 3 months. This was a guy who worked had previously worked in a corporate jet program.

His first introduction to how govt contract works was on his first day. A line of storms were approaching the field and he an another new guy started moving equipment inside the hanger so it didn't get damaged. Was told by his supervisor not to touch it because it's not in their contract to do so. This was his biggest gripe. Everything was done by bare minimum and only what's in the contract. They would hurry through whatever task assigned and then spend the rest of the day sitting in the corner playing dominos. Told me they hired farm equipment sheet metal workers who had little experience with aircraft and had no attention to detail. Witnessed several times workers damaging aircraft because they treated it like a tractor and not a helo. The final straw for him was when his supervisor told him his tool box would be used for a no notice "random" inspection coming up. No one had any accountability of their tools and they were a mess. His were immaculate.

His final day his supervisor called him into the office, baffled at why he was quitting and asked him what the problem was. He flat out told him he thought their maintenance was so poor that he didn't even like the fact these "f'ing things" were flying over his house! Of course that gave me incredible confidence, because I had to fly them everyday.:(
 
I think we took it for granted the aircraft were't airworthy when we went to pick them up; on some occasions, we just refused to take 'em, got back on the airlines and went home. The managment there tried arm twisting a couple times, but we were Reservists, so they had no leverage. Once we found a puddle of pee on the floor, which made no sense, since there was a urinal (drains overboard) within a couple feet if the puddle. That ended that pre-flight.
 
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