Craig,

You might want to check the aneroid bell on the fuel pump, as on one occasion after reaching about 100 feet after takeoff my fuel flow went to over 50 gals causing belching black smoke and the engine shuddered from getting way too much fuel.  Checked things on once back on the ground, couldn’t find anything, went back up, and had the same problem.  I had the aneroid bell on the fuel pump rebuilt and tested all the fuel flows on the metered and unmetered sides to assure they were in normal range and the problem was gone.  Mike, the mechanic at our local FBO watched my second takeoff, which also caused lots of black smoke, and  immediately suggested the aneroid bell problem as he had seen it in the past.  Thanks to him, he saved me weeks of hard work that you have obviously encountered. 

 

Hope this helps and gives you something to look at.

Pat

 

-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Craig Berland
Sent: Monday, August 24, 2009 7:25 PM
To: lml@lancaironline.net
Subject: [LML] IV-P Manifold Pressure Problem

 

I have a newly flying TSIO-550 powered IV-P with a persistent and nasty problem.  On takeoff roll the manifold pressure is steady at 38.4 in Hg and the fuel rate is steady at 43 gph.   The engine runs very good up to this point.  At 50 ft AGL the manifold pressure starts to run away.  If left unattended it will climb to 43 In Hg and the fuel rate will chase the manifold pressure and go to 54 gph at which time the engine starts belching black smoke and looses power.  We have never let it go past this condition but it appears the engine would likely stop running if left unattended.  The plane accelerates very good from 0 kts to 90 kts.  At 50 ft AGL the plane is at 120 kts.  I have inspected all of the pressure reference lines going to the boost controller , I have had the controller rebuilt by Main Turbo, and I have applied air pressure to the waste gate and it operates normally.  The very odd twist is the first few flights were very normal and manifold pressure was steady the entire time.  We fixed a heavy right wing by changing the wing incidence of both wings and the problem started on the very next test flight.  I have ordered a new controller and it should be available in the next few days.  We have also found that the manifold pressure wonders 0.3 in Hg in level flight and will decrease in a climb and increase in a decent by approximately 1.4 in Hg.  This is all happening between the airport altitude of 330 ft and 4500 ft while making laps around the airport.  The problem seems to be steadily  getting worse.  However having the engine quit making power at 50 AGL is pretty bad….so getting “worse” may not be to relevant.

 

Any ideas as to what is wrong?  This problem has stumped quite a few industry experts.

 

Craig Berland

N7VG  IV-P