Ethics of Misdiagnosis
Vložit
- čas přidán 12. 04. 2023
- When an aircraft owner puts his aircraft in the shop and asks his mechanic to fix a specific problem, should the owner have to pay for work done or parts installed that don’t resolve the issue? That's the question the owner of a vintage Piper PA-12 Super Cruiser posed to maintenance expert Mike Busch. The question triggered a fascinating exchange between Mike and the owner about the ethics of misdiagnosis, and that's the subject of this webinar. Mike discusses what owners can do to avoid being victimized by this all-too-common situation. Savvy Aviation offers Professional Maintenance Services to owners of General Aviation aircraft, such as: SavvyMx (Professional Maintenance Management), SavvyQA (Expert Consulting), SavvyPrebuy, SavvyAnalysis (Engine Data Analysis) and Breakdown Assistance. Savvy also publishes a monthly newsletter with lots of interesting information for the general aviation enthusiast; subscribe to it at www.savvyaviation.com or text the word "Savvy" to 33777. This webinar was hosted by the Experimental Aircraft Association (EAA).
- Auta a dopravní prostředky
Second! I’ve done all my own maintenance, including engine rebuilds, for the past 30+ years. The only way to own an aircraft is to know it, every nut and bolt of it.
I'm thinking that the mechanic should have been able to prove the primer was either bad or working fine and the same with the magneto before replacing thing
I love your video and have been following you for years, you have helped me understand a great many things as a maintainer of my own light sport aircraft in Australia.
But I have to-dis agree with you to some extent here.
I understand you point about the problems a mechanic may have diagnosing a particular problem.
But as an owner, who is being asked to pay a significant hourly rate, I expect a degree of expertise.
If someone wants to work in the military or a large shop and be given a job card with the work to be done that is fine with me.
But if they want to hang a sign on their shed and say "bring your problems to me" they should take some responsibility for the decisions they make spending "other people's money"!
These guys have a monopoly to perform work on aircraft. In many cases the owner is quite capable of performing that work, but is prohibited by regulation.
I agree, the owner needs to take responsibility.
For example, if a mechanic suggested the appropriate response to a lean idle mixture was to replace a carburetta, I would drag my aircraft out of his shop by the propeller if necessary!
I remember talking to a friend of mine 40 years ago, he was an Australian LAME ( your A &P, I guess) and I was helping him restore a vintage military aircraft.
He lamented the age of the advent of a "black box" mentality, 40 years ago.
If there is a problem, don't diagnose, just change the major component, change the "black box"!
I remember my son coming to me 20 years a go with a car alternator that had failed, he could not afford the replacement that the mechanics said was necessary.
I said to him, "it is probably just the bushes", I went to the parts store and bought the carbon bushes.
One screw, un-clipping 2x spade clips and re-connecting the new bushes and , "hey presto", a working alternator!
All for $5.00!
A few years ago a local mechanic started business.
I took my car to him for an Oil and filter change, something I would normally do but i thought I would try him for convenience.
when i picked it up he told me they had done a "water treatment" on my fuel tanks with out asking, My 4WD has two tanks.
$40 dollars a tank! $80 for NO value!
I run that car on E10 ethanol fuel, so a "water treatment" was totally un-necessary, the ethanol absorbs and disolves any water and it isburned with the fuel, it does not settle in the tanks!
I have never gone back and I have warned every local I know about his bad practice.
I am sure his short term $80 has cost him a lot more than that over the years.
If someone hangs a sign on their wall, they imply a level of expertise.
If they want to substitute parts, maybe they can use known old parts to isolate the problem.
If they want to "throw darts" with other people's money they should be outed, with negative recomendations to all the aircraft owners you know!
Some years back, a friend was telling me about some odd high frequency vibration down the back of his C182. It would only appear when he leveled out and went through 90 knots. He checked the antennas, fairings, you name it, couldn't identify it. He asked if I wanted to see it for myself - sure, let's go. He said "it's down the back some place." So I jumped in the back seat, not the front.Takeoff, level out 90 knots - bzzzzzzzzzzzz there it was. Friend said "See, it's down the back somewhere!" Ah no, it's coming from IN FRONT of me! So I look around the cabin and spy an air vent up near the door pillar. I adjust the vanes with the shutter lever and it stopped. And I could bring it back just as easily. The vanes were acting like a reed and vibrating in that sweet spot. My friend had been chasing this fault for months.
I had a piper that would kick when started on both. It was noticeably smoother when started on the Left (impulse) mag . It’s amazing how easy it is to just read the manual.
Just realized that Mike is Socrates of aviation. Thanks for all you work 👍
Thank you...
It comes down to running a business. I just had a case where the shop put someone on the problem with questionable experience and I ended up paying 16 hours of shop time for him to diagnose a problem that would have been spotted almost immediately if he had used any systematic approach to isolate the problem. The shop should have called me put let someone fiddle with it for 2 days called me and said they found the issue never mentioned or asked if they could run up a bill.
At Savvy we give the shop a reasonable amount of hours to do their troubleshooting, say 2, and say "if you're still unsure what to do, consult back with us." We do not give them carte blanche to tackle a problem, and don't recommend that~!
I just looked up what an impulse coupler is/does. It is a device that ensures the magneto produces enough spark to ignite the fuel/air mixture in the cylinder regardless of how slowly the crankshaft (propeller) is turning. Which means if the magnetos are not shorted to ground (ignition switch in off position) the engine could start by just moving the prop so that a tow bar could be installed. Which means you should always verify that the ignition is off before moving the prop and even then be prepared for the possibility of the engine starting if the ignition switch might be defective. Perhaps a student pilot should be told to never move the prop until he gets his license.
Piper did this for hand propping purposes on the J-3 cub. Much less chance for the plane to get away from a pilot on a single mag hand prop than both mags.
To me the issue here is that this mechanic obviously took zero time to perform any diagnosis or troubleshooting. He just kept throwing parts at it, hoping something would stick. To add insult to injury, after he finally had the owner perform the lean idle test (which is the first thing that should have been done), the recommendation was to replace the carbureator instead of the few minutes it would have taken to adjust the idle mixture.
I understand that A&P currently has no legal requirement to demonstrate or know anything about the equipment they work on other than how to replace parts to meet factory spec. What is appalling to me is that so many treat this almost like a union benefit - it shall not be expected to be otherwise. I was fortunate that the A&Ps I dealt with were also good technicians/diagnostics - they literally had to be since they were in small shops in rural areas. We would always discuss what was happening, look at engine data (if it was a powerplant issue). After an appropriate discussion and input, we would both agree what was going to happen. If parts were required, I would generally acquire them myself after insuring what was required. I also shared communication/recommendations from input from the SavvyMX support personnel.
I do agree that anyone that just drops off an aircraft with the command - its broke, fix it, is probably not going to like the end results.
I have a good friend who is an auto diagnostician. He fixes cars after shops or customers “fire the parts cannon.” His motto is “test, don’t guess.” I think Don should make sure he get all the old parts back because they are fine. He needs to fire his A&P because he is incompetent in power plant diagnosis and find someone who can fix it.
I have mixed feelings on this. Any mechanic should strive to pinpoint a problem. When I hear that a whole carburetor is suggested, I am suspicious. I moved into aviation 30 years ago from motorcycles, where carb issues are rampant, due mainly to car gas, lots of sitting, and very small jets, air bleeds, etc. Tiny, and more troublesome than aircraft carbs. We fixed them. To sell a whole carburetor was very unusual, a failure to fix it.
Aircraft carbs are relatively large (clogs less likely) and very simple, and are fed well filtered avgas that stores well.
So, new carb needed? Not likely. Maybe they don't want the associated liability.
On the other hand...your MD analogy is excellent. The complaining customer probably went to a shop with minimal equipment to diagnose anything, with a mechanic making pay equal to or a little better than an Amazon warehouse employee..working with tools he was expected to buy, after paying for truly antiquated rigidly controlled FAA A&P training. The curriculum is full, and controlled to the minute, and if that is all of your training, you will probably NOT be adept at troubleshooting.
He should have taken his piper to one of those shops with all available diagnostic equipment, staffed with only top notch experienced troubleshooters.
I haven't seen such a GA shop. Around here, aircraft maintenance is significantly cheaper than car maintenance...the aforementioned top notch shop, if it exists, should probably reasonably get $200/hr. So, at that price, it wouldn't exist for long.
You won't get perfection from shops equipped and staffed like I see...just as you don't with Healthcare that might be twenty times the price.
Same guy again. On the starting issue- if the P-leads are switched at the switch, starting in the "L" position would result in starting without the benefit of the impulse coupling. No hot spark.
And, starting with the advanced spark, if it is strong enough to spark well at cranking RPM, can be dangerous.
I saw an io-540 break its crankcase...two non-impulse coupling mags were installed, just for "test purposes", the correct mag was apart or something. The engine kicked back. The old bendix style starter stayed engaged, part of the nose of the starter broke, and cracked the crankcase starter mount pad by one of the studs or bolts.
I was watching it, and felt lucky to have wondered out loud whether or not that was a good idea.
Clearly, it was not.
2 Things: First, aviation seems to suffer from the same malady as the automotive repair field; tryagnostics and swaptronics. Second; is it possible that the impulse coupling mag was installed on the wrong side? Was this ever checked?
The owner should not have to pay for the mechanics incompetence !!
I say this as a lic. A&P.
Type clubs are amazing resources
At a minimum, id start with the simplest, cheapest option when in doubt.
I do a lot of headwork long before I contact the owner and propose a repair. If I am not 100% sure it is going to fix the problem I have a discussion with the owner and explain how I got to my decision and ask him how they would like proceed. This way going in everyone is on the same page and know the possible results. I have spend hours trying to find issues on an airplane that I am not familiar with that someone with that specific aircraft knowledge would have found sooner. I do not feel right charging all the hours spent due to my low knowledge base of that particular aircraft. At the end of the repair I look at what a person with good knowledge of the airplane would have probably taken to do the same repair and that is what I bill. I look at this time I did not get paid for as my cost of education and education is not free and I do not think an aircraft owner should have to pay for my education. They should have to pay as if I had the knowledge base.
I don't think that comparing mechanical maintenance with medicine is a very good track to take.
Your doctor cannot disassemble you to your individual components, inspect the functionality of those components, test how they are interacting with other, and positively identify which parameters need to be tweaked. But that's exactly what the process of maintaining/repairing any machine is.
When I take my plane to the mechanic, there's an implicit expectation that the mechanic is going to competently identify the cause of the problem before he starts swapping parts out. If the mechanic is unable to positively identify the cause, I expect the mechanic to tell me that before playing Russian Roulette with the parts catalog to try and solve it, and I don't believe that expectation is unreasonable.
Engines are extremely simple machines. All they need to work is fuel/air in the correct ratio, compression, and a source of ignition. Each of these items can be diagnosed independently without much trouble, and certainly without needing to just throw parts at it and see what happens.
If the engine won't start, the process of figuring out why is very simple. Check the compression. Test the spark plugs. Test the magnetos. Check that fuel is reaching the carburetor. If the plane has an impulse coupler, test that. If it uses a shower-of-sparks, test that. The only item on this list which cannot be instantly verified in-situ is the mixture coming out of the carburetor. As such, it should be left for last, as removing and inspecting/cleaning the carburetor is invasive and expensive.
I'm writing this comment at 17 minutes into the video. Given that the problem began only when the owner began starting with the mag on L instead of BOTH, I'm betting on one of two root causes:
1: magneto switch wired improperly, L is actually R
2: magneto switch is physically damaged/has dirty contacts and the left mag is remaining partially or fully grounded with the mag in the L position.
There's always a balance between troubleshooting hours and part prices. It wouldn't be an issue to shotgun parts if they weren't so expensive, but they are.
OK Fine, I’ll look into getting an engine monitor, start collecting data, and join the Savvy cult. Because you are absolutely correct the A&P IA has been simply grasping at tools and parts. I will miss flying a hard VFR wood, tube, and fabric biplane that barely has enough of an electrical system for starting. I will miss the dogmatic dedication to the purity of flight. However ongoing misdiagnosed and undiagnosed issues are getting old and preventing ANY flying.
I was thinking Don should have tried starting with both mags again to see if that "fixed" the hard starting, and then tried starting on just the right mag to see if the starting performance was different from both or left. Maybe the impulse coupling was on the right mag instead of the left on his plane. This testing wouldn't cost a thing and I expect the results of the testing would be enlightening. I'm surprised the mechanic recommended replacing the carb instead of trying to adjust the idle mixture which would have been much faster and much cheaper. If I were Don I'd go find another mechanic. Of course, being me, if I owned a plane it would be experimental so I could do all the work myself, as I do with my vehicles.
I definitely agree with you that asking your mechanic "what issue did you discover that indicates that XXX needs to be replaced/repaired?" "is there an adjustment that you could make instead of replacing the part?" Basically prove to me you have done due diligence to find the smoking gun before spending my hard earned money.
The whole thing is very simple... why change the way you have been starting the engine...DUH ! Now if it doesn't start well after the annual, get back with the mechanic. If it ain't broke, don' fix it ! ...What, are we bored ?
Diagnosis starts with a complete understanding of your aircraft systems, combined with experience and genuine interest in flying in general. Remember, YOUR ASS IS IN THE PLANE as well as your family and friends... insurance be damned. Get interested in life ! Certainly, if flying is part of it.
Wait, aircraft mechanics are not trained on diag?
There is such a disparity between mechanics you need to know who you are dealing with. The idea of just replace parts is done by inexperienced mechanics or ripoff artists. As an IA, I would never do this. I don't replace something unless I can prove or convinced its bad. If you send a plane into fix a problem and they replace parts that don't fix the problem, you are not responsible to pay. they didn't fix the problem. simple as that. Bottom line, make sure you trust the mechanic that does the work.
Yes you are responsible to pay Jew bag
Hello Mike, since you weren't able to make changes to the A&P rating and you wrote several books, maybe you can publish a guide to an systematic approach to engine diagnostic for the A&P.
"Mike Busch on Engines" does have a chapter or two about interpreting engine monitor data. I'm not sure I could fill an entire book with that, but I'll consider it. Thank you.
As a mechanic I think it is downright unethical and borderline criminal to throw parts at a problem at the customers expense. You are supposed to diagnose the issue and then test stuff not throw parts at the problem! Seriously this isn’t rocket science and a GA aircraft is a very very simple machine compared to a modern car, this is really basic stuff equivalent to working on a lawnmower especially a vintage aircraft like this.
I think the comparison between the treating of a migraine and a hard starting plane is a pretty bad analogy. Did the A/P have any evidence the primary was bad ? Was there any reason to believe the magneto was bad ? I didn't see any evidence mentioned in the story. This mechanic is throwing very expensive parts at a problem without a lot of thought. Get rid of this mechanic and save yourself a lot of time and money !!
The problem is most pilot/owners are tight wads. The reality is most A&P's have your safety and best interest in mind...just let them do their job and pay the bills! If you don't like it then pay the bill and find a new shop the following year. This holds true 99% of the time.
You are 100% wrong.... owner/pilots get screwed by mechanics, and don't get the problem fixed. You guys are lazy and expect to get paid for coffee breaks you take most of the day. TRUTH HURTS
@@daleyingling4868 salty troll much?
Also sounds like you’ve never actually been in a professional shop and not your weekend AP whose willing to work and take on liability for a 6-pack.
@Caleb P Wrong: I spend $50,000 to $250,000 every year for maintenance of several aircraft, including jets, and prop aircraft. You know nothing about how 90% of A&P from the local guy to large 145 stations rip off customers in the aircraft maintenance game. One of the reasons that the FAA is considering off the shelf parts for repair of aircraft.
@@daleyingling4868 sure.
Never though it’d cost money to keep aircraft airworthy. Sure there’s definitely crappy shops out there, but it’s not a plague as SA treats it.
Most a&p’s I’ve found can’t properly diagnose a broken pencil.. they are part bolt’er on’ers that are hacks at the expensive of owners.
Aircraft Maintenance is like Healthcare without insurance.
It sounds like it’s okay to throw away money in the medical field since it’s third parties paying for it. That is a gross misconception. It never is. And shouldn’t be.
First !
Ah yes, the parts cannon!