ZamF16 Posted July 28, 2016 Report Share Posted July 28, 2016 (edited) On a recent trip from Denver to San Antonio at 17k' with the engine set at cruise (29/2400), my MP suddenly dropped to 24 and the fuel flow had a corresponding drop. I immediately increased the throttle to bring the MP back up to cruise (it took close to full throttle). It seemed as if the turbo was no longer providing boost. While I verified the engine was otherwise running correctly and identifying my nearest divert, I felt the turbo kick back in and the engine came back to full power. This cycling continued every 10 minutes or so for the remaining hour of flight. We pulled the wastegate and the controllers and took them into the local shop for troubleshooting. The controllers appear to be the culprit. One is leaking oil, and the poppets are sticking on both--need overhauling. The overhaul is being done the week. I will let everyone know the outcome. Dave Edited July 28, 2016 by ZamF16 Quote Link to comment Share on other sites More sharing options...
FlyDave Posted July 28, 2016 Report Share Posted July 28, 2016 Dave, Sorry to here you had this issue - it doesn't sound like fun in the air! How many hours on your engine/turbocharger? Any precursors you can think of prior to this failure? Please do keep us posted. Thanks, FlyDave 1 Quote Link to comment Share on other sites More sharing options...
ZamF16 Posted July 29, 2016 Author Report Share Posted July 29, 2016 No precursors. It was a complete surprise. When I lost the manifold pressure, I was in the area over west TX where airfields are sparse. As I lost thrust, I sucked the seat cushion right up my...well you get the picture. While the shop says both controllers need to be overhauled, I really don't understand exactly what was happening. I got the two controllers and the wastegate back today. The overhaul of all 3 cost just over $3k. I am hopeful that this resolves the problem. I'll post updates as I learn more. Dave 1 Quote Link to comment Share on other sites More sharing options...
ZamF16 Posted July 29, 2016 Author Report Share Posted July 29, 2016 To your other questions, the engine has 1918 total time with the turbo overhauled about 150 hours ago. The wastegate and controllers are original equipment as far as I can tell from the records. Quote Link to comment Share on other sites More sharing options...
N231BN Posted July 29, 2016 Report Share Posted July 29, 2016 It could be the turbo bearing going out too, I have seen a twin cessna do the same. Quote Link to comment Share on other sites More sharing options...
ZamF16 Posted July 30, 2016 Author Report Share Posted July 30, 2016 (edited) On July 28, 2016 at 11:43 PM, N231BN said: It could be the turbo bearing going out too, I have seen a twin cessna do the same. Inspected the turbo. Luckily it is in pristine shape. We are reinstalling the wastegate and controllers early next week. I will know soon if that solves the problem. Edited July 31, 2016 by ZamF16 1 Quote Link to comment Share on other sites More sharing options...
DVA Posted August 2, 2016 Report Share Posted August 2, 2016 I’m interested to find out what happened. Anytime you have a MAP change (significant) in stable cruise in a turbocharged airplane it is an immediate indication to land ASAP. There are so many bad things that can happen based on a turbo component coming loose, including a fire danger. Two temps that are not normally monitored are Compressor Discharge and Inlet Air. I always suggest that these are added as they can be a big help in identifying problems. Do you have these monitored, and if so, can you look at a engine monitor history file? Quote Link to comment Share on other sites More sharing options...
ZamF16 Posted September 4, 2016 Author Report Share Posted September 4, 2016 I have about 8 hours on the new waste gate controllers. My throttle response is smoother than ever before. In fact I am realizing how bad I had it for years. I have always had a jump in thrust at about 25" MP as the turbo would all of a sudden spin up. Now I get smooth throttle response all the way up. However, I do notice that my max MP is now about 35", instead of the 36-37 I had before. I will have that adjusted. Quote Link to comment Share on other sites More sharing options...
Hank Posted September 4, 2016 Report Share Posted September 4, 2016 Your turbos didn't completely fail. I generally get about 20" at 10,000 msl, and my one trip to 15,000 msl (18,800 DA), I don't remember the MP but I was step climbing the last several thousand feet. Doubtless, though, it was an uncomfortable experience. Glad everything seems to be okay now. Quote Link to comment Share on other sites More sharing options...
donkaye Posted September 4, 2016 Report Share Posted September 4, 2016 14 hours ago, ZamF16 said: I have about 8 hours on the new waste gate controllers. My throttle response is smoother than ever before. In fact I am realizing how bad I had it for years. I have always had a jump in thrust at about 25" MP as the turbo would all of a sudden spin up. Now I get smooth throttle response all the way up. However, I do notice that my max MP is now about 35", instead of the 36-37 I had before. I will have that adjusted. Maximum manifold pressure is a function of the temperature, and the density controller controls it. 36"-37" is way too high and is generating more than 100% power. Not good for engine longevity, although your engine is pretty much run out anyway at 1918 hours. I wouldn't trust it in IMC with that time on it. The red line at 38" doesn't mean it should be set to that. From my 24 years experience and 2 engines 35" is where it should be nominally set. Quote Link to comment Share on other sites More sharing options...
DVA Posted September 4, 2016 Report Share Posted September 4, 2016 In support of what donkaye just said, here is the graph from the Lycoming manual used for the static setting of the density controller at full throttle. You’re probably set up for the first time in a long time correctly at 35”. The MP sensor also has a tolerance of +/- 1” so don’t get too finicky here, you are just fine exactly where you’re at. Quote Link to comment Share on other sites More sharing options...
ZamF16 Posted September 4, 2016 Author Report Share Posted September 4, 2016 Copy, on the max MP. I will leave it alone. I just was so used to seeing it at 36" on the previous waste gate controllers that 35" got my attention. Quote Link to comment Share on other sites More sharing options...
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