In an earlier posting today I mentioned a separate fuel injection setup for the Cirrus that was revealed to us by a former TCM engineer. This individual was contacted when we learned of the overheated cylinders in N142CD. I spoke with him on the phone today for a clarification of what I thought had been said, and he made clear to me that this setup procedure is known to Cirrus and that they use it. This was not quite the same as what I heard 48 hours ago but I admit that something may have been lost in the
note taking. I now seriously doubt that the problems in this engine were caused by an incorrect fuel injection setup.
Compounding this doubt is that I queried him about the altitude compensation system in the fuel injection pump. We felt it was not working properly, if at all, on the flight out. Specifically, I asked why we got 17 gph fuel flow on takeoff from an airport at 6000 feet msl. His calculations revealed that the system should have automatically reduced full throttle fuel flow to 15 gph at that altitude. So if anything, the setup was too rich and not too lean.
What was the cause of the problem? It certainly was not caused by anything that occurred on our 12 hour flight from Duluth to Hayward. Other than that, your guess is as good as mine.
What matters most is that Cirrus did the right thing by insisting that the engine be replaced. It will be installed by a Cirrus tech and initially flown by a Cirrus pilot before being released to Rob Leach for the ferry (after compression check, oil change, filter inspection, etc.) I was impressed by our factory tour, by the flight to Hayward and by the eventual success of Cirrus in demanding a new engine. Although the Grumman Tiger has been my choice for 22 years, I think all of you folks have a winner in this airplane and in its manufacturer.
Thank you, Bill. Clyde, in light of this and your recent followup message in the other thread, do you (or anyone else) know what the process will be for getting to the bottom of this problem? Or, is it going to be: “fix the ones that break and don’t mess with the ones that don’t…”?
Thanks.
What was the density altitude? Isn’t that what the altitude compensation is looking at.?
Compounding this doubt is that I queried him about the altitude compensation system in the fuel injection pump. We felt it was not working properly, if at all, on the flight out. Specifically, I asked why we got 17 gph fuel flow on takeoff from an airport at 6000 feet msl. His calculations revealed that the system should have automatically reduced full throttle fuel flow to 15 gph at that altitude. So if anything, the setup was too rich and not too lean.
What was the cause of the problem? It certainly was not caused by anything that occurred on our 12 hour flight from Duluth to Hayward. Other than that, your guess is as good as mine.
In an earlier posting today I mentioned a separate fuel injection setup for the Cirrus that was revealed to us by a former TCM engineer. This individual was contacted when we learned of the overheated cylinders in N142CD. I spoke with him on the phone today for a clarification of what I thought had been said, and he made clear to me that this setup procedure is known to Cirrus and that they use it. This was not quite the same as what I heard 48 hours ago but I admit that something may have been lost in the
note taking. I now seriously doubt that the problems in this engine were caused by an incorrect fuel injection setup.
What matters most is that Cirrus did the right thing by insisting that the engine be replaced. It will be installed by a Cirrus tech and initially flown by a Cirrus pilot before being released to Rob Leach for the ferry (after compression check, oil change, filter inspection, etc.) I was impressed by our factory tour, by the flight to Hayward and by the eventual success of Cirrus in demanding a new engine. Although the Grumman Tiger has been my choice for 22 years, I think all of you folks have a winner in this airplane and in its manufacturer.
Bill: Thanks for the clear answer and the FACTS. I guess we’ll all have to wait and see what ends up happening with the engine.
Clearly it is not in TCM’s interest to deny a problem, so I’m sure (or very naive) that this will be cleared up soon. Unfortunately it looks like the forst 50 or so SR20 owners may end up as test pilots.
Thank you, Bill. Clyde, in light of this and your recent followup message in the other thread, do you (or anyone else) know what the process will be for getting to the bottom of this problem?
I have no doubt Cirrus will be wanting to unravel the mystery as much as we do, but don’t expect to get any progress reports on this. But I do not for one moment think they will write it off as “one of those things”. They need this plane to build a reputation for reliability, and the engine is a crucial part of that.
I’m gathering information at present but I don’t expect to have any quick answers. I’m also looking at whether we can claim our incidental expenses from TCM (about $6000 so far). Their warranty expressly excludes these, but we have a moral claim, and possibly a legal one, that they should reimburse us for what it cost to sort out the dud engine we bought.
What was the density altitude? Isn’t that what the altitude compensation is looking at?
Did not compute it, but it was a warm day so the DA was at least as high as MSL. All over the western USA this is a fairly typical situation in all months but the coldest ones of winter.
As to the altitude compensation, I don’t know if the Continental system aneroid corrects for both temp and pressure or just pressure. The only one I can recall off hand that senses both is the system in the Navajo. My guess is that the Cirrus system senses only atmospheric pressure.
Rob Leach is back in Hayward and I asked him earlier today to research the POH on the altitude compensation system. Info was scarce and all it said was basically that it sets the correct mixture for takeoff when the mixture control is full rich. That was my concern about it. I noted no difference in fuel flow regardless of the altitude of the departure airport. I wondered what the purpose was of an automatic leaning device if it didn’t automatically lean. Hopefully this is unique to this one engine that is being replaced.
Bill,
At one point in you flight out you noted that it was hard to start and you had to prime it until fuel was dripping out. (something like that)
Could this be any indication of the altitude compesating not functioning properly?
Possibly so. It was one of the squawks I wrote up for the Australian owners. We primed it to the
point where fuel was flowing out the overflow
and then tried a flooded start procedure. It would not hit on even one cylinder. A call to the
factory said, “prime it some more.” We were
incredulous but did what they said and it worked. We had never seen this with any other
Continental engine and as a result, neither of us was satisfied with the dripping fuel or with the explanation we were given. Hopefully the replacement engine will make this a non-issue.
Bill,
At one point in you flight out you noted that it was hard to start and you had to prime it until fuel was dripping out. (something like that)
Could this be any indication of the altitude compesating not functioning properly?
After additional thought, there might be some concrete connection with the altitude compensation system. When this happened there was a lot of fuel running out of the bottom of the cowling, so much that we thought it a fire hazard. Until Guy’s post, I had only assumed it was fuel drained from the cylinders due to excess priming.
However, after the engine had its problems and was uncowled in Hayward, I noticed that there were (I believe) four or five sources of fuel that all came together at the drain point on the bottom fuselage aft of the cowling. One of these was from the intake manifold drain from the cylinders, one from the sump drain, one or two came from the fuel injection pump and I think one came from the fuel injection spider unit.
When priming, the electric fuel pump pushes fuel through the fuel injection pump and on to the cylinders. However, if there was a problem with the altitude compensation system (this start problem occurred at about 5000 feet MSL), possibly much of the fuel we saw going overboard was coming from the fuel pump drain and never reached the cylinders.
I don’t have ready access to the service manual, but would be very interested to know if there is some fuel path in the fuel injection pump that could send some prime fuel to the pump drain in addition to the cylinders.
Not of much interest to the pilot in me, but the A&P part finds the issue challenging.