Originally posted by Habu
I have a JPI engine analyzer which shows each cylinders temp and EGT plus the oil temp. All were normal. The fuel gauges were normal. The oil pressure and temp gauges on the dash were normal. In Canada we call them AME (Aircraft Maintanance Engineer). When the gauges went wacky I was just as much in the dark as to what was causing it as you.
I landed at the first opertunity and had a trusted AME check them out. On the ground everything was fine. I took him for a circuit and it was fine. After I landed and he got out I flew back to my home airport and the problem happened again. It was then I figured out how all these supposedly unrelated gauges were all being affected together.
A couple questions here first.
What make / model plane were you flying?
Do you have the tach and manifold pressure displayed on digital or steam guages. Digital like the JPI.
Were you in icing conditions? I assume you were VFR or that the IFR guages were functional.
Are the VSI and altimiter digital?
I ask these questions as the typical small plane has seperate systems for engine and flight guages and only 2 would be related for input.
Example, the altimiter and manifold pressure both require a static port for ambient pressure otherwise they are not related systems wise.
The tach is typically a cable driven item and has no relationship guage wise to the others.
IF you have a complete digital engine display system with tach, manifold pressure, cyl temp., oil temp and pressure these could be affected by a bad ground and give erratic readings. That would not explain the altimeter and VSI. A static port partially obstructed would do that. Provided the altimeter is connected to a shared static port with the VSI. That presupposes you have a non pressurized aircraft.
You need to provide additional info. to make the diagnosis.
