Engine cutting in and out multiple times at altitude in 231

[warrennn]

Last Monday I flew from Concord, CA to Paine Field in Everett, WA at 20,000 (to avoid ice) in my '79 231 with the TSIO360LB engine. I was getting a huge tailwind (>70 kts) and would have made the trip in < 3 hours. After 2 hours, the engine started misbehaving: it would nearly shut off and immediately return to normal power. It did this numerous times, with maybe 20 seconds between events. I got priority handling to land at Eugene, passing through a lot of IMC in the process. Below 10,000 or so, the engine started behaving normally and I landed safely. BTW, the controllers were extraordinarily helpful during the entire process.

There are no full time available mechanics in Eugene, but one person did some investigating online and via the people at Teledyne and thought it was a leak in the turbo waste gate. My mechanic at home thought it might be frozen water in the fuel line. I had checked the tanks and found no water. I didn't drain the sump (mistake?) It is surprising that the engine ran fine and decided to fail after 2 hours if sump water were the culprit. I finally decided it was likely an altitude dependent problem and flew home at 6000 - the engine didn't miss a beat.

I of course will not fly until the engine is thoroughly checked.

I have an ESG ADS-B with a 2i ADSB in device which I use with Foreflight. I didn't realize the 2i doesn't have a backup battery. I will replace the thing with a 2s, which does have a battery. An engine failure would result in no gyros, which would be a problem - the HSI which Foreflight provides would be a big help in case of an engine failure in IFR.

In my 26 years of owning this airplane, I have had only one other instance of a similar problem (previous engine). Nothing was found. Anyone have any ideas about what happened? Thanks!

wn

 

Edited March 29, 2019 by warrennn

[larryb]

Did you happen to observe the fuel flow during the episode? What was the OAT? Do you use IPA at altitude and winter? Ice crystals in the fuel are a possibility. 2 hours at altitude is a good amount of time to get the fuel good and cold.

Other thought is a pressurized mag problem.

[M016576]

10 minutes ago, larryb said:

Other thought is a pressurized mag problem.

That’s what I was thinking- maybe a mag/electrical issue.

The one time I had ice in my fuel system, the ice blocked the intake at the gascolator.... the motor wasn’t surging- it was just losing fuel pressure continuously and nothing I did helped... until I pulled the gascolator drain as a “Hail Mary”... which happened to purge the blockage and restored full pressure and power immediately.

 

if you do think it’s fuel system blockage- a great place to start would be to take apart your gascolator and check the screen.

[ArtVandelay]

No engine monitor data?


Tom

[exM20K]

Fuel or spark.  Engine monitor data will tell the tale.  

 

Fuel: low boost to suppress vapor lock.  Engine monitor data will show fluctuations in pressure or flow.

spark: pressurized mags maybe not pressurized and crossfiring.  

Or, ignition harness has a bad lead.  Lop test at altitude will help.  Game site has the protocol

-de

Edited March 30, 2019 by exM20K

[warrennn]

Thanks all for your prompt responses!

Unfortunately, I didn't notice the FF. Some time ago, I replaced the FF transducer with one with a much smaller k-factor and the analogue needle hardly moves. I was so focused on finding a place to land that I didn't notice the digital (Shadin) fuel flow.  I did notice large drops in the manifold pressure - I assume the FF was low as well. I have had high altitude mag problems about 15 years ago and the manifestation is very different from what I observed: there is a thump when the engine misfires. Even when the engine suddenly lost power, it was always smooth.

Unfortunately, I don't have an engine monitor. I never run the engine LOP - it is always about 100 degrees rich of peak with a FF of about 13.3 g/hr. 

I am thinking that I had water in the fuel even though my fuel cup was dry when I checked before flight.

Thanks again!

wn

[Marauder]

1 hour ago, warrennn said:

Last Monday I flew from Concord, CA to Paine Field in Everett, WA at 20,000 (to avoid ice) in my '79 231 with the TSIO360LB engine. I was getting a huge tailwind (>70 kts) and would have made the trip in < 3 hours. After 2 hours, the engine started misbehaving: it would nearly shut off and immediately return to normal power. It did this numerous times, with maybe 20 seconds between events. I got priority handling to land at Eugene, passing through a lot of IMC in the process. Below 10,000 or so, the engine started behaving normally and I landed safely. BTW, the controllers were extraordinarily helpful during the entire process.

There are no full time available mechanics in Eugene, but one person did some investigating online and via the people at Teledyne and thought it was a leak in the turbo waste gate. My mechanic at home thought it might be frozen water in the fuel line. I had checked the tanks and found no water. I didn't drain the sump (mistake?) It is surprising that the engine ran fine and decided to fail after 2 hours if sump water were the culprit. I finally decided it was likely an altitude dependent problem and flew home at 6000 - the engine didn't miss a beat.

I of course will not fly until the engine is thoroughly checked.

I have an ESG ADS-B with a 2i ADSB in device which I use with Foreflight. I didn't realize the 2i doesn't have a backup battery. I will replace the thing with a 2s, which does have a battery. An engine failure would result in no gyros, which would be a problem - the HSI which Foreflight provides would be a big help in case of an engine failure in IFR.

In my 26 years of owning this airplane, I have had only one other instance of a similar problem (previous engine). Nothing was found. Anyone have any ideas about what happened? Thanks!

wn

 

Aren't the mags supposed to be sealed on the 231s? I would look at the mags. I couldn't imagine water taking that long to show up and then mysteriously go away.

[gsxrpilot]

It doesn't sound like water in the fuel to me either. But then again, I've never once sumped water out of my tanks. And if I ever did, the O rings would be changed immediately. 

I can't imagine flying the TSIO360 turbo without an engine monitor. Or at least I'll say I can't afford to fly a K without an engine monitor. And respectfully, you have no idea how many degrees ROP you are without an engine monitor.

It sure sounds like a wastegate issue to me. But then without an engine monitor you're either guessing, or IRANing everything... which will cost a bit more than a good engine monitor.

[larryb]

The water we are talking about here is not the liquid water you would drain from the sump. It is dissolved in the fuel. At very cold temperatures it can freeze, and those crystals can block the fuel filter or other parts of the fuel system. IPA (Isopropyl Alcohol) can be added up to 3% to prevent this. I have a few gallons of 99.9% IPA that I add occasionally and especially if I am planning a long high cold flight.

 

Larry

 

https://www.sae.org/standards/content/air790c/

[DanM20C]

I'm thinking it is fuel related.  It doesn't sound like a mag or wastegate issue. You either have a fixed wastegate or a Merlin.  It it's fixed nothing is going to change at alt.  If you have a Merlin it will be fully closed well before FL200.  I can't imagine a failure note that would cause them to cycle from close/open/close quickly.  Generally Merlin's suffer a slow silent death and then just get stuck.  Then they behave the same way a fixed wastegate does.  

I had a mag pressurization problem once too and the engine started missing above 16K.  It ran rough but didn't shut down and come alive.

I would have your mechanic take a close look at the fuel system, specifically the engine driven fuel pump.

I completely agree with @gsxrpilot about having an engine monitor paired with a TSIO-360.  They help run the engine safely ROP or LOP and they offer so much in the way of trouble shooting it's amazing.  Plus my engine monitor may have helped me get to an airport when my #4 cylinder decided to come apart.  Without the engine monitor I would have just felt/heard a few little pops and I may have continued on as the engine was running smooth.  But I immediately diverted because I could see #4 had gone cold.  A few min later the cylinder head broke loose, breaking the intake and fuel line.  The intake nuts, washers, and other bits of metal were sucked into the intake and made a mess of everything.   An engine monitor is a must have for me.

Cheers,

Dan

[warrennn]

The mags in the 231 are pressurized from the intake manifold (?). 

That cylinder head failure sounds terrifying! I must say, if I heard any "pops" from my engine, I would have looked for a place to land.

When I had a mechanic at Eugene suggest a cause, he did a lot of web searches and spoke to the manufacturer and heard that the most common cause of what I experienced was a leaky waste gate. 

Well, in a few weeks my local mechanic will try to find the cause of the problem. Until then, I will keep out of high altitudes.

wn

[DanM20C]

12 minutes ago, warrennn said:

The mags in the 231 are pressurized from the intake manifold (?). 

That cylinder head failure sounds terrifying! I must say, if I heard any "pops" from my engine, I would have looked for a place to land.

When I had a mechanic at Eugene suggest a cause, he did a lot of web searches and spoke to the manufacturer and heard that the most common cause of what I experienced was a leaky waste gate.  

Well, in a few weeks my local mechanic will try to find the cause of the problem. Until then, I will keep out of high altitudes.

wn

You are correct, the mags are pressurized off the intake.

The "pops" I experienced were not unlike a misfire.  I'm most certain I would have carried on if I didn't have the indication that #4 was cold (egt/cht). 

You never mentioned if you have a fixed or Meryln wastegate?

Cheers,

Dan

[Aerodon]

My money is on an induction leak.  Compounded if you have a Merlyn waste gate.

Mags or fuel icing won't do anything that regular.  If the engine starts losing power at 20k, it's a massive downward spiral - less exhaust, less boost, less power, less exhaust.  And maybe over rich mixture to boot.  You lucky it didn't quit all together and only restart at a lower altitude.  Quite frankly I'm surprised the power came back at all.

Then at lower altitude, the induction system is not nearly as susceptible to induction leaks, including all the pies and fittings that control the merlyn and fuel flow.  We once had a leaking merlyn control hose, and the engine was quite unstable until the manifold pressure was brought back to below ambient pressure.  Then these hoses don't 'leak' inwards or outwards,.

Second bet is on exhaust side of turbo - leaking clamps or joints, or bypass.  But I don't see that 'repairing itself' and the white residue is easy to spot.

Do let us know the end result. 

One final comment - I believe all 'mechanical' diversions are reported to the FAA, and they do follow up from time to time.  So returning to flight without a proper diagnosis, repair and signature could cause you a problem.  (I may well be misinformed with this statement).  But personally, resuming flying with an unsolved problem will be really difficult to explain to the FAA or your insurance company if things were to go wrong.

 

Aerodon

[ilovecornfields]

51 minutes ago, Aerodon said:

 

One final comment - I believe all 'mechanical' diversions are reported to the FAA, and they do follow up from time to time.  So returning to flight without a proper diagnosis, repair and signature could cause you a problem.  (I may well be misinformed with this statement).  But personally, resuming flying with an unsolved problem will be really difficult to explain to the FAA or your insurance company if things were to go wrong.

 

Aerodon

I highly doubt the FAA is going to get involved. I declared an emergency and made a precautionary landing once because of an engine issue. There was ZERO paperwork for me or any sort of follow-up. The Fire Captain even offered to give me a ride home.

On the other hand, flying with an unresolved potentially signifigant engine problem requires bigger cajones than I possess. Fortunately, in my case  I was able to download my engine data and submit it to Savvy and after some quick troubleshooting with the mechanic at the field I was comfortable that the problem had been addressed.

[231LV]

Yikes! Nice job keeping your head when everything is turning to crap quickly....I second the above suggestions for an engine analyzer....well worth every penny as it lets you see, at a glance, whats happening inside the jugs. I'm replacing my JPI 800 with an (OEM qualified) JPI 900 which takes all the steam gauge dials out of the cockpit including all the gauges across the top of the glare shield.....with Sun and Fun, you can grab a new JPI 800 for $2700.....this would allow you to safely run LOP where life is sweeter...great job getting down in one piece!

Edited March 30, 2019 by 231LV

[warrennn]

Thanks! At one time I thought there was a chance we would not make it back but was able to divert my attention to getting on the ground in one piece. 

I do not have a Merlyn waste gate - just the stock fixed one. I do have a Precise Flight intercooler. 

I did consult with a mechanic on the field who thought I could make it back at lower altitude. My home mechanic also thought I was ok flying it back and he is very conservative. So far no FAA calls. For what it is worth, I didn’t use the E word. 

 

 

Edited March 30, 2019 by warrennn

[carusoam]

1)fuel

2)spark

3)air/turbo

Erik can give a good description of what happens when a turbo fails at altitude...

@M20Doc might have some experience as well...

Having a JPI full of data would have a half dozen people reviewing the data by now...  

Did you see any changes or bouncing MP indications?

Good luck with the next steps...

Best regards,

-a-

As For draining the sumps... it gets done in my hangar all the time.  Too much risk to not drain them...

[warrennn]

I had a turbo fail at 15k about 15 years ago. The manifold pressure just went down to 20" or so and didn't come back up. I returned to my home field and found that the exhaust pipe had slid out of the fixture and directed the exhaust at the front of the cowl (causing a burning smell). The thing was held in with wire wrapping which failed. It had also happened after takeoff when I smelled something burning and quickly turned around and landed.

 

[warrennn]

During these engine drop-outs, the manifold pressure would drop precipitously and immediately come back up to normal.

[Guest]

It’s really hard to diagnose from my iPad with the cowls still on, but induction system or exhaust system failure comes to mind.  Pull the cowls and pressurize both systems with a shop vacuum.

Clarence

[carqwik]

I'm betting on ice crystals...

Is your plane hangared at CCR?

[warrennn]

No, it is in a hangar at Paine Field in Everett, WA (KPAE). Ice in fuel or waste gate problems would be my guesses. 

[231LV]

22 hours ago, warrennn said:

During these engine drop-outs, the manifold pressure would drop precipitously and immediately come back up to normal.

You are almost describing a "lean stumble" where the engine is running so lean that the engine will "hiccup". Of course, this can only happen when LOP. I would suspect Mag arching at altitude...ice crystals in the fuel might cause this, as well....of course, we are all just guessing but it does seem associated with high altitude/cold temps.

[kortopates]

On 3/30/2019 at 3:28 PM, warrennn said:

I do not have a Merlyn waste gate - just the stock fixed one.

 

3 hours ago, warrennn said:

No, it is in a hangar at Paine Field in Everett, WA (KPAE). Ice in fuel or waste gate problems would be my guesses. 

The stock fixed wastegate is only a bolt that blocks part of the exhaust going to the turbo - its not a real wastegate, it doesn't move and thus won't be responsible for your problem. Ice crystals is a definite possibly but easily cured by adding some isopropyl alcohol to the fuel and a good prophylactic step anyway. But first step needs to be to simply remove the cowling and inspect induction, exhaust and turbo. What you describe doesn't really sound like bootstrapping, but another possibility, but that could have been checked by increasing the RPM assuming you could give it a couple hundred more rpm to see if that cured it (going lower fixes that too).

If your A&P does a thorough inspection and doesn't find anything a amis, you could put some isopropyl Alcohol in per your POH (it doesn't need much) and do a test flight to altitude. 

As many folks have already said, an engine analyzer can help eliminate a lot of things (like high alt misfire) even if it can't exactly pinpoint the problem. But as someone else said above, having one and knowing who to use it can really make the difference between flying till engine failure versus getting an alert that something in wrong and getting back on the ground before the engine fails. I can't imagine flying without one these days both to protect my precious cargo as well as my wallet; somewhat just like GPS and onboard weather.   

Edited April 1, 2019 by kortopates

[81X]

Just because I had a personal experience- how long has it been since your fuel system has been overhauled?  Mine was something like 14 years and the o rings that came out of it were severely dryrotted and fortunately only left me stranded on the runway and not 10 seconds later.  This also means new o rings in the gascolater, and selector valve.  

It's likely not the wastegate- the fixed one has one failure mode and if it breaks, it won't fix itself at 10K.  Only a slight chance it's the popoff valve.  

I do also like the arcing mags idea if they aren't the pressurized ones.  

Were you running low boost?  I think we're supposed to run it over 18K or something like that in the 231's to avoid vapor lock in low pressure environments.  

+1 million for an engine monitor- you will be surprised how much those factory gauges are off.