Engine Instruments to Have

[leeschaumberg]

To know how your engine is running you need to know some things.
1. Hour meter Couple to the oil pressure so it runs when the engine does.
2. Oil Pressure Your engine requires the proper oil pressure.
3. Oil Temperature This makes sure the oil cooler is working.
4. Engine Temperature or Water Temperature On air cooled engines pick a spark plug base temperature.
5. Voltage There is no need to monitor charging amps when you know the voltage stays where it should (14.5) or so when running. If it goes down it means the alternator is not replacing all the power used.
6. EGT 1 Each cylinder produces heated exhaust gas when it is making power.
7. EGT 2 See above
8. EGT 3 See above
9. EGT 4. See above
10. Engine Air In The inlet air temperature determines how much power the engine will develop.
11. Manifold Air Pressure When turbocharged or supercharged the air entering the engine than the ambient air pressure.
12. Fuel Pressure When there is fuel in the tank and the fuel pump is working there will be a positive pressure.
13. Fuel Flow When the engine is leaned properly for the altitude the fuel flow will be proper.
14. RPMs or Tachometer It's always good to know how fast your engine is running.
Many glass cockpit type displays don't have everything you need.
It is good to have a (green lite) when things are working.
Have a (red lite) when an out of range ocurs or you have a problem.

[Jeff R]

When you say hour meter, do you mean a Hobbs, or do you mean the hour meter that is on the tach guage?

If you mean a Hobbs, I am curious as to why. I thought all maintenance requirements were based on tach time.

[leeschaumberg]

The hour meter can be any bodys as long as it records real engine time.
This list comes from my BRAIN not cut from some list.
It does not contain any flight instruments.

[az_gila]

Originally Posted by Jeff R

When you say hour meter, do you mean a Hobbs, or do you mean the hour meter that is on the tach guage?

If you mean a Hobbs, I am curious as to why. I thought all maintenance requirements were based on tach time.

Not really.. to be precise the FAA bases time for maintenance on flight hours - the FAA calls it "Time-In-Service". There are a few AC docs that give the details.

Bottom of page 3 of this document, as an example...

Long, ugly FAA link

In practise, this is difficult to do and the tach time is used as an approximation. The mechanical tach time gives hours of engine operation based on a specific cruise rpm.... run at 1/2 the cruise rpm, and time takes twice as long to record.....

Some digital tachs just count time above a rpm threshold (800 rpm on my Horizon)

The true way to record time would be a timer based on an airspeed threshold, as in some of the newer panel mounted GPS units. I'm not sure how the different EFIS guys do it....

Of course, all of this is not critical in our homebuilts, since we do not need maintenance hours for AD compliance.

gil A

PS.... this is for maintenance, your pilot logged hours are different...