Fuel injectors cleaning

[EricJ]

10 minutes ago, DCarlton said:

I retired from the Navy after 35 years as a civilian engineer.  That's where I developed my paranoia regarding maintenance induced failures.  Every time someone turns a wrench, removes a healthy component, and reinstalls it, I somehow need to understand it's necessary even if it's just reading the recommended service bulletins.  But yes, understand if you're a professional mechanic you have to follow recommendations otherwise, you'll get eaten by that bear you mentioned.  A few mechanics know their customers and their customers airplanes and operating environment well enough to know what makes sense though and how to steer them where to invest in phased maintenance.  But again, I'm no expert, just a guy with an opinion.  

Many agree with you, notably Mike Busch, who cites the supporting studies often.   FWIW, many of things the people often say are required really aren't, like annual wheel bearing packing.    As replacement materials and lubricants have changed over the years it is not at all unreasonable to adjust guidance made nearly a half century ago or more.

https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2011-03_the-waddington-effect.pdf

 

[GeeBee]

The only time I've ever had a bad injector was the one that was not fully tightened after annual cleaning.

[A64Pilot]

The problem with on condition maintenance is determining inspection intervals and damage tolerance. That takes a whole lot of data sampling across a fleet.

At the test activity we often flew components well beyond limits, (Bearcat 41 and Bearcat 43) we had two AH-64’s that we did that on, called lead the fleet aircraft, they had more hours than any other AH-64’s. Book max tolerance on Pitch Change links was .020, we flew them past that and tried to determine when wear rate became excessive, since .020 was the generic max tolerance on all Army Heim joints regardless of size or duty. All the test stuff was orange, those aircraft had lots of orange stuff, and it was intensively monitored.

The Military and Big boys have bunches of money to determine mean time between failures etc, max damage tolerance, actual failure limits etc. For our older out of production aircraft, it’s just not going to happen, who would fund it?

The current system has worked well for a long time, good luck trying to change it.

Maybe Cirrus?

[Shadrach]

3 hours ago, A64Pilot said:

You follow the checklist, if Mooney and or Lycoming had wanted it done on an hourly interval, don’t you think they would have done so? But they didn’t. I don’t know why.

The point us, is don’t put yourself on a pedestal and think your smarter than them, it’s a hard position to defend, especially if something goes South.

Where are they cracked, fuel line side?

Military we did “phase” inspections, every 250 hours, and the crew chief did a through pre-flight ever 10 hours or 14 days whichever occurred first, we did not do major Calendar inspections that I can remember, but we aren’t Military. We are under FAA jurisdiction. I used to tell people I worked for who had the opinion that they owned the Company not the FAA, and therefore they could do what they wanted, that the FAA is like a Bear in the woods, you walk by the path for years and never see the Bear, pretty soon you wonder if there really is a Bear so you get lax, then one day for seemingly no apparent reason the Bear shows up and rips you to pieces.

It seems they really had rather not do their job, they had rather sit in the office, but if your going to make them fill out all this paperwork etc., they are going to push it and there will be some king of enforcement action. 

Using your logic then how far a leap is it to decide an Annual is silly, I mean the thing only flew 20 hours last year, after all the inspection is usually called 100hr / Annual so why not wait until 100 hours?

It can be a slippery slope once you start, so don’t start is the only thing I know to do.

We used to have a saying in the Army for you to think about before you did something, “how will it brief to the accident investigation board?”

Once the video was found, this one didn’t brief so well

I do five or six Annual’s a year, owner assisted and I’ve never charged my friends and neighbors, but will let them buy lunch or something. I’ve never made money from being an A&P / IA

Many may squall about the owner assisted part, but I figure it’s had two sets of eyes on it and I’m operating just as an inspector and I think it’s better / safer than me doing the work and inspecting myself. That was one difference in the Military, person performing the work was never allowed to inspect their own work.

Maybe you could get some Lawyer to argue the check list is just a guide and you can do whatever you think is important and only do AD’s, but I don’t want to be sitting there arguing that, don’t think it would brief well.

Annuals are regulatory.  Debating whether some other interval would add to or detract from safety is another conversation, and a legitimate one. 

Regulatory Inspection requirements are in 43 appendix D. Mooneys list is guidance and is a broad list covering all models. We use it as a guide and will continue to do so. However, I am not repacking wheel bearings that have done less than 50 miles just because it’s on a guidance list. 

There are lots of instances where my ops differ from factory guidance. I don’t reduce MP in the climb because my POH says so. I set power based on digital temperature readouts, not POH power tables.  Thankfully guidance and recommendations are not regulatory… not because it’s a bad idea to follow them, but because knowledge and understanding is not static and occasionally we learn that there are smarter ways to do things.  If I bend metal or make a smoking hole in the ground or and a lawyer is able to convince a jury it it was due to wheel bearing grease intervals or 500hr injector cleaning, than that jury could be convinced of many things.   43 appendix D does not specifically state that injectors need to be removed nor wheel bearings repacked.

I’ve had two maintenance induced injector problems. The cracked ones in the photo resulting from a mechanic overtightening the b-nuts. Don’t know exactly who or when but have my suspicions. The second problem was discovered when I pulled the engine for the case crack in 2009. #1 injector was not properly torqued and had loosened. It was chattering and was beating up the threads.  This was the year after a $10k repair station annual.

 

 

[DCarlton]

8 minutes ago, Shadrach said:

Annuals are regulatory.  Debating whether some other interval would add to or detract from safety is another conversation, and a legitimate one. 

Regulatory Inspection requirements are in 43 appendix D. Mooneys list is guidance and is a broad list covering all models. We use it as a guide and will continue to do so. However, I am not repacking wheel bearings that have done less than 50 miles just because it’s on a guidance list. 

There are lots of instances where my ops differ from factory guidance. I don’t reduce MP in the climb because my POH says so. I set power based on digital temperature readouts, not POH power tables.  Thankfully guidance and recommendations are not regulatory… not because it’s a bad idea to follow them, but because knowledge and understanding is not static and occasionally we learn that there are smarter ways to do things.  If I bend metal or make a smoking hole in the ground or and a lawyer is able to convince a jury it it was due to wheel bearing grease intervals or 500hr injector cleaning, than that jury could be convinced of many things.   43 appendix D does not specifically state that injectors need to be removed nor wheel bearings repacked.

I’ve had two maintenance induced injector problems. The cracked ones in the photo resulting from a mechanic overtightening the b-nuts. Don’t know exactly who or when but have my suspicions. The second problem was discovered when I pulled the engine for the case crack in 2009. #2 injector was not properly tightened and had loosened. It was chattering and was beating up the threads.  This was the year after a $10k repair station annual.

 

 

Appreciate the 43 Appendix D reference.  I'm not sure I've ever read that; or it's been a long time.  What is written, definitely describes a physical inspection and not much more.  

[N201MKTurbo]

30 minutes ago, DCarlton said:

Appreciate the 43 Appendix D reference.  I'm not sure I've ever read that; or it's been a long time.  What is written, definitely describes a physical inspection and not much more.  

You are correct, but how do you inspect wheel bearings without repacking them? How do you inspect injector nozzles? You might as well clean them while they are out.

[DCarlton]

2 hours ago, N201MKTurbo said:

You are correct, but how do you inspect wheel bearings without repacking them? How do you inspect injector nozzles? You might as well clean them while they are out.

Perhaps wheel bearings are on the annual condition inspection list to do everything possible to avoid runway closures.  Would be interesting to know the history.  

[EricJ]

2 hours ago, N201MKTurbo said:

You are correct, but how do you inspect wheel bearings without repacking them? How do you inspect injector nozzles? You might as well clean them while they are out.

The standard method on nearly anything else with wheel bearings is to check play.   That's pretty easy.  It's also pretty easy to check for escaping grease or other relevant issues without exposing the bearing.  If you have an engine monitor you can "inspect" nozzles every time you run the engine. 

[EricJ]

21 minutes ago, DCarlton said:

Perhaps wheel bearings are on the annual condition inspection list to do everything possible to avoid runway closures.  Would be interesting to know the history.  

In my observation flat tires close far more runways than wheel bearings.

[N201MKTurbo]

I only mentioned that because an FAA principal inspector said that to me once.

[Shadrach]

3 hours ago, EricJ said:

In my observation flat tires close far more runways than wheel bearings.

I wonder if we’d see less flat tires if we deflated the tubes every year and removed for visual inspection.

[A64Pilot]

16 hours ago, DCarlton said:

Perhaps wheel bearings are on the annual condition inspection list to do everything possible to avoid runway closures.  Would be interesting to know the history.  

I believe it’s from long ago when wheels didn’t have grease seals and many or most flew off of grass, a couple inches of a 5” tire sunk into soft ground can easily get water in it. In other words it’s probably not required now, but to remove an inspection is tough, you basically have to be able to prove they are unnecessary, and proof is harder than you might think, so we get stuck with ancient things 

Then if you brought up that wheel bearing failures are a one in a million occurrence, who you’re arguing with’ s answer would that’s because there are inspected and repacked yearly. Circular argument. So do you check that block, but not do it? That’s falsifying aircraft records and that’s a serious offense.

But you know just like the lawyer letter in another post where they are fishing for one plug being the reason or at least a contributing factor in a death, when the FAA said it was pilot induced. I’d bet lunch they will prevail and get mucho money.

If for some reason something happened to a main landing gear, say a seized brake caliper, I can guarantee if it goes to court a Lawyer will claim inspecting the wheel bearings would have prevented it, because the brakes have to be removed to get the wheel off. I’ve seen it before, as I was subpoenaed as an Expert witness once or twice, it’s a jury trial and the defendant is sitting there with tears rolling down her face with a baby in her lap, you think a jury isn’t going to award her money to educate and care for the baby?

You wouldn’t believe how crazy the lawsuits are, they shotgun everybody hoping to pick up money here and there, Hartzell really was sued in the accident where some sports guy and his instructor flew a Cirrus into a Building in NY I believe, I was told it was because their prop pulled the airplane into the building, though I’m sure they were just one of a great many being sued.

How to defend skipping recommended inspections?  You can’t there is no defense, not one that a Lawyer wouldn’t pick apart immediately.

Fact is we live in a litigious society, and I’m Retired and had significant assets, enough to keep me until I’m 90 at current living standards (at least I used to, before before current economic realities) and fact is I could lose those with a stroke of a pen. I’m even very careful who I take with me flying, because I’ve seen that go bad too.

 

[N201MKTurbo]

12 hours ago, Shadrach said:

I wonder if we’d see less flat tires if we deflated the tubes every year and removed for visual inspection.

I do.

[jimp45]

Sure


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