I’m sorry, this is not a relevant post for this forum, but at this point I’m willing to ask anybody and everybody for advice. There’s a large group of people here, maybe somebody has an idea for a problem I have. Here goes:
I fly a Learjet for a private owner. The engines are Honeywell TFE731–20BR. Roughly 20 minutes after takeoff, usually right before reaching FL430, I get a red EICAS and a red master warning, ‘RT ENGINE BLEED AIR’. Supposedly a leak in the bleed air system of the right engine. The entire bleed air detection system has been throughly inspected, the fire loop has been replaced. There is no bleed air leak. The red messages/warning continue to occur.
The light extinguishes when I turn off the rt bleed air and idle that engine for 20 seconds or so. The passengers don’t like it when they hear an engine rolling back at FL430, it scares them. The light goes out, I bring the engine back and the light won’t come back on till the next cycle.
The A&P who does the wrenching can’t figure it out, says, ‘don’t worry about it’.
I’m not worried, the owner is. I think it’s an EICAS computer glitch. Any experienced turbine A&P’s that might be here have any suggestions?
I told the owner that we are going to get to the bottom of it.
I just want to say up front I am no jet engine expert; but, There has to be at least one sensor of some type (mechanical or digital) to detect the "leak" in the bleed air and set off the master caution. (Yes, you know that and so does your mechanic) If the sensor(s) checks out as good and short of replacing them (hanging parts) it could be an EICAS computer. I was not an engine guy so I'm just spitballling but I'm more inclined to think it's a sensor and not a computer especially since you are not getting the warning on the left engine. Of course, you can always hang a new computer but I'm betting the sensors are less expensive than a computer. When we transitioned to the Blackhawks we had sensor issues occasionally but I don't ever recall a "computer" failing. (EECU)
It's just that the fault repeats itself at a certain altitude and once the system is recycled (engine idled) everything is happy. I am inclined to believe it is a pressure sensitive (altitude) sensor that has to catch up with itself. I'm guessing your rate of climb is better than 2000 feet a minute even at altitude and something in a sensor is slow like a bellows (mechanical) or a resister that catches up with itself when you go to idle the sensor acclimates to the altitude.
Just my thoughts.
kwg
