Junkman

When to overhaul the turbocharger?

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Is there an indication of when a turbocharger is in need of overhaul?

I am approaching 1000 hours on my turbo since its last overhaul (before my ownership), and from all performance measures that I can see from the cockpit it is still doing its job without degradation. I've read here that some folks overhaul at 1000 hours - is that based on time or performance? I've also read that the turbo can last to the engine TBO. I'm a fan of IRAN/IROC in most cases so I'd like to know what I can be looking for to indicate the repair/replace is drawing near. I've searched here but didn't come up with anything that answers this for me, and although I'd guess that a decrease in performance and abnormal whining sounds from the firewall is what I should be looking for (like in a car) I'm not one to guess when it comes to my airplane...

Cheers,
Rick

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While waiting for an answer... I bet there are things to be looking for...

1) oil useage becomes part of the equation...

2) oil seals have a tendency to let oil out from where it is supposed to stay.

3) turbine blades can turn into turbine nubs...

4) Signs that something may need looking into...

  • oil coming out of the exhaust
  • Max MP not getting developed like before
  • oil turning dark quickly after oil change

This is just Ideas to get the ball rolling. Not actual experience...

Best regards,

-a-

 

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I would have your mechanic inspect it. 

Pull the intake coupling off and inspect the compressor wheel. Feel it for smooth rotation and end play. Use a borescope up the tail pipe to inspect the turbine wheel. Inspect the turbine housing for cracks. 

This should all be done at annual anyway. If all is OK, Then I would say if it ain't broke, don't fix it. It should make it to TBO.

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1 hour ago, carusoam said:

Signs that something may need looking into...

  • oil coming out of the exhaust
  • Max MP not getting developed like before
  • oil turning dark quickly after oil change

 

1 hour ago, N201MKTurbo said:

Pull the intake coupling off and inspect the compressor wheel. Feel it for smooth rotation and end play. Use a borescope up the tail pipe to inspect the turbine wheel. Inspect the turbine housing for cracks. 

1 hour ago, N201MKTurbo said:

BTW,

The best thing you can do for your turbo is change your oil often and don't run your TITs to high.

Thanks Gents!

1. Oil consumption has been 1 quart every 12-13 hours since 2016.

2. Oil stays more golden than dark through oil change, when it is a dark golden brown (not black).

3. Religious oil changes at 25 hours or less.

4. TIT at cruise is 1600-1625 running LOP at 13.8gph; 1530-1560 running ROP at 18gph .

5. Performance has been consistent since 2016, with MP at the top of the band on takeoff and stable in cruise.

I haven't borescoped the tailpipe/turbine, will do that next trip to the hangar to have an uneducated look. I don't know that the cold side of the turbo has been opened during our ownership for inspection of the compressor, so will put that on the list for the annual in August. Based on engine performance, I really don't expect to see anything bad. 

Not broke = don't fix. Got it. With regular attention and TLC toward ROC, I think the airplane likes this, too. Almost as much as my wallet does.

Cheers,
Rick

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I would agree with your position. If it is performing well and no oil leaks, then I would leave it be.

If you do need an overhaul, RAJAY is considered an OEM and can offer very competitive pricing on Factory Remans to new specs with a 1000 hour / 2 year warranty.

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I don’t know of any hard parameters, my Bravo was built in 12 2004, I decided based on personal ideals I’d send out the turbo for rebuild at the 500 hour mag rebuild. My turbo went for rebuild at 479 hours, most I spoke with felt I was overly cautious, in light of recent posts it will go out prior to the next 500 hour interval.

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500 hrs is very conservative and considering the limited reuse of Turbo vbands is certainly going to increase your maintance costs.Do you also rebuild the waste gate controller at same interval?

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My turbo was obviously rebuilt at engine overhaul some 1100 hrs ago.

i fly ROP only. 35 25 climb to cruise then 31 24 or 30  22 dependent on wind.

almost always 100 rop which almost always transfers to 1600 tit.

i know the Lame checks endfloat thru exhaust at annual. Also know v clamps were put on at engine overhaul and have not been removed - they are single use due to a few failures in the early days.

always change oil at 25 hrs and always cool engine before shutdown.

I had a wastegate problem at 1700 hrs on the original engine but had no history of what was done to the turbo before that.

I’d be more concerned with the condition of the exhaust system than rebuilding the turbo.

In fact next annual my exhaust will be coming off and going to the exhaust shop for evaluation.

so new v band clamps and maybe some exhaust work.

 

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5 hours ago, Steve Skinner said:

My turbo was obviously rebuilt at engine overhaul some 1100 hrs ago.

i fly ROP only. 35 25 climb to cruise then 31 24 or 30  22 dependent on wind.

almost always 100 rop which almost always transfers to 1600 tit.

i know the Lame checks endfloat thru exhaust at annual. Also know v clamps were put on at engine overhaul and have not been removed - they are single use due to a few failures in the early days.

always change oil at 25 hrs and always cool engine before shutdown.

I had a wastegate problem at 1700 hrs on the original engine but had no history of what was done to the turbo before that.

I’d be more concerned with the condition of the exhaust system than rebuilding the turbo.

In fact next annual my exhaust will be coming off and going to the exhaust shop for evaluation.

so new v band clamps and maybe some exhaust work.

 

1) The Mooney marketing department was the driving force back in the late 80's when the TLS was being developed. They wanted the fastest piston single sop the numbers in the POH weren't realistic for good engine life. 31/24 is a bit high for cruise. The combined number you want to shoot for on a Bravo is 53, 31/24 would be 55. When the TLS first came out people were running at 34/24 and going through cylinders every 300 hours.

For awhile Mooney and Lycoming weren't on the same page. When Lycoming suggested lower power settings after a lot of top end overhauls Jacques the president of Mooney at the time vowed never to use another Lycoming engine in a subsequent Mooney. In reality the 29/24 setting still yields so me pretty incredible speeds.

2) V-bands I believe are limited to two re-torques, not single use, meaning that after initial install in can be re-torqued twice.

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Sooo... I reported on another thread that I assumed that the Pre-buy / Annual performed by Dugosh (a Mooney Service Center) that I paid for during the purchase of a 1995 Bravo with 2400 hrs TT would be reasonably complete.  I expected it to include a thorough evaluation of AD's, previous maintenance history and for them to flag anything that was of concern due to time in service, overhaul intervals or inspected condition, etc. 

After delivery, I began to discover (along with my local mechanic), numerous issues that are listed in the other thread (exhaust valve going bad, exhaust system leaking, turbo issues)

As for the turbo, it had never been overhauled.  Upon learning this, I made the call to have it removed and overhauled.  Here is a photo of the oil leakage inside the turbo that was discovered upon removal.  
In retrospect, I did not personally review the AD's or logs as closely as I should have as I assumed I was paying a trusted professional to do it for me.  

BTW, there were performance related signs that the turbo was not performing properly. 

 

inside turbo.jpg

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14 minutes ago, alextstone said:

Sooo... I reported on another thread that I assumed that the Pre-buy / Annual performed by Dugosh (a Mooney Service Center) that I paid for during the purchase of a 1995 Bravo with 2400 hrs TT would be reasonably complete.  I expected it to include a thorough evaluation of AD's, previous maintenance history and for them to flag anything that was of concern due to time in service, overhaul intervals or inspected condition, etc. 

After delivery, I began to discover (along with my local mechanic), numerous issues that are listed in the other thread (exhaust valve going bad, exhaust system leaking, turbo issues)

As for the turbo, it had never been overhauled.  Upon learning this, I made the call to have it removed and overhauled.  Here is a photo of the oil leakage inside the turbo that was discovered upon removal.  
In retrospect, I did not personally review the AD's or logs as closely as I should have as I assumed I was paying a trusted professional to do it for me.  

BTW, there were performance related signs that the turbo was not performing properly. 

 

inside turbo.jpg

If I were you I would try to get the pre-buy shop involved and participating in the cost of making this right. Obviously some of these things are airworthiness issues which you would have insisted be rectified by the seller had they been flagged by the pre-buy, which I am assuming is one of the major reasons  you were having the pre-buy done in the first place.

Edited by Bravoman

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1 minute ago, Bravoman said:

If I were you I would try to get the pre-buy a shop involved and participating in the cost of making this right. Obviously some of these things are airworthiness issues which you would have insisted be rectified by the seller had they been flagged by the pre-buy, which is obviously one of the major reasons  you were having the pre-buy done in the first place.

Trust me, I am planning on doing just that.

 

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Well... good luck with requiring pre buy shop to pay for ANY subequent repair issues!Goodluck Alex with your up coming legal issues...

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PPIs are lacking any standards...

Hope you have some written documentation for what you were asking or something that covers what they promised to cover...

Certainly AW issues are critical and usually are the basis for the PPI...

Good luck, be prepared for the conversation...

As for common turbo challenges...

- the oil seals wear over time and start leaking oil... Not too expensive to get fixed...

- thinning of the tubing from the exhaust valve to the turbo... happens over time.  The weakness can lead to cracks and blow torch results...

- definitely know how many times your V clamps can be used. And how many times they have been torqued.  Having one fail is another blow torch event... An unknowing mechanic can really ruin your day.  Many mechanics are not aware of the sensitivity of the Vclamp issue.

As an owner, your biscuits are at risk, not your mechanic’s... know these details for your own health...

PP thoughts only, not a mechanic...

Best regards,

-a-

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5 hours ago, carusoam said:

PPIs are lacking any standards...

Hope you have some written documentation for what you were asking or something that covers what they promised to cover...

Certainly AW issues are critical and usually are the basis for the PPI...

Good luck, be prepared for the conversation...

As for common turbo challenges...

- the oil seals wear over time and start leaking oil... Not too expensive to get fixed...

- thinning of the tubing from the exhaust valve to the turbo... happens over time.  The weakness can lead to cracks and blow torch results...

- definitely know how many times your V clamps can be used. And how many times they have been torqued.  Having one fail is another blow torch event... An unknowing mechanic can really ruin your day.  Many mechanics are not aware of the sensitivity of the Vclamp issue.

As an owner, your biscuits are at risk, not your mechanic’s... know these details for your own health...

PP thoughts only, not a mechanic...

Best regards,

-a-

Perhaps prebuys don’t have much in the way of standards but annuals certainly do. The OP made clear both here and on the other thread  it was both. If it was me I would make it my business to make sure that a shop that fell below the standard of care to my detriment (certainly on airworthiness issues) made me whole. When it comes to aircraft maintenance with what is at stake it would be principle to me. 

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Thanks for all of the good advice.  I am not a litigious person by nature so I am going to try to work out a fair compromise with the MSC.  I am also now committed to being intimately involved with every aspect of my aircraft's maintenance.  I went to the shop last night to have a look at the progress on the install of the turbo and exhaust system discuss the V-band AD with my mechanic.  To his credit, before I could mention  the V-bands, he showed me which ones he was replacing and explained why, exactly in line with the AD.  I hope that my negative posts have not given you a false impression of my personality.  This was a tough lesson.

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1 hour ago, alextstone said:

Thanks for all of the good advice.  I am not a litigious person by nature so I am going to try to work out a fair compromise with the MSC.  I am also now committed to being intimately involved with every aspect of my aircraft's maintenance.  I went to the shop last night to have a look at the progress on the install of the turbo and exhaust system discuss the V-band AD with my mechanic.  To his credit, before I could mention  the V-bands, he showed me which ones he was replacing and explained why, exactly in line with the AD.  I hope that my negative posts have not given you a false impression of my personality.  This was a tough lesson.

I'm not familiar with the M20M turbo installation, but it may not be the turbo that is causing that oil puddle. That oil can only accumulate with the engine off. It would turn to blue smoke if the engine was running. The seals in the turbo are not absolute seals, they will allow oil to enter the turbo if it is not running. I would check the check valves in the oil system if this engine has them.

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Could be that the scavenger pump is not scavenging enough. I had this with my K. There is a test for that which can be done. As I understand it turbo oil leakage is not really a seal issue but instead a scavenger pump or check valve issue.

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1 hour ago, larryb said:

Could be that the scavenger pump is not scavenging enough. I had this with my K. There is a test for that which can be done. As I understand it turbo oil leakage is not really a seal issue but instead a scavenger pump or check valve issue.

Hi Larry,

 

  Any info you can provide on this test would be appreciated.

 

Ron

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Hi Larry,
 
  Any info you can provide on this test would be appreciated.
 
Ron

I was having oil drip out of the exhaust in the hours after shutdown. My shop did the test, I did not. As he described it they disconnect the two oil hoses from the turbo and put them in a can. Then they run the engine at a certain rpm and make sure the pump can empty the can faster than the supply hose fills it. My engine failed the test and I wound up buying two new scavenger pump gears.

There is also a proper turbo shutdown procedure. As described by my shop you should run the engine at 1300 rpm for 30 seconds then pull the mixture and shut down. This allows the scavenger pump to get the oil out of the turbo.

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My airplane has 3895 hours on it.  It was on its 2nd engine before the shop mishap a couple of weeks ago.  Shortly, it will be on its 3rd engine.  The turbo on the first one lasted about 1300 hours before I began hearing hissing noises.  Somehow the blades got chipped.  It was overhauled.  Awhile later the waste gate needed to be overhauled.  On the 2nd engine, I proactively overhauled the turbo, waste gate, and controllers at about 1300 hours again.  The controllers never controlled properly on descent.  So, from experience, I would overhaul all turbo components including waste gate and controllers at half TBO at a time of  your choosing rather than having to do it at some out of the way place at a time NOT of your choosing.

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Friend who runs a Lycoming powered Malibu reckons on changing turbos at 1000 hours (in line with Don's recommendation), although in that application they have a harder time due to cabin pressurisation. A previous owner of my aircraft got through a number of turbos in short succession, at least one due to ice damage. The last one made a bit over 1000 hours before I had to change it due to  a collapsed bearing

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On 10/18/2018 at 9:54 AM, alextstone said:

Thanks for all of the good advice.  I am not a litigious person by nature so I am going to try to work out a fair compromise with the MSC.  I am also now committed to being intimately involved with every aspect of my aircraft's maintenance.  I went to the shop last night to have a look at the progress on the install of the turbo and exhaust system discuss the V-band AD with my mechanic.  To his credit, before I could mention  the V-bands, he showed me which ones he was replacing and explained why, exactly in line with the AD.  I hope that my negative posts have not given you a false impression of my personality.  This was a tough lesson.

Articulate, negotiate, and if that doesn’t resonate, litigate!:D

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On 10/19/2018 at 2:50 AM, Awful_Charlie said:

Friend who runs a Lycoming powered Malibu reckons on changing turbos at 1000 hours (in line with Don's recommendation), although in that application they have a harder time due to cabin pressurisation. A previous owner of my aircraft got through a number of turbos in short succession, at least one due to ice damage. The last one made a bit over 1000 hours before I had to change it due to  a collapsed bearing

The Lycoming TIO-540-AE2A on the Malibu Mirage uses two turbo chargers, so twice the fun (expense) !

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