If you are not doing an instrument check before an IMC flight (pretend or real) you might as well skip the runup too...after all what you don't know can't hurt you right
I second the advice about firing your instructor.
A few more points on instrument checks and please note these are meant for your average club fixed gear simple trainer with a standard basic 2 NavComs, ADF, and transponder radio package. First off at the risk of being a bit pedantic, there are actually two separate and distinct pretakeoff IMC checks.
Instruments (flight and flight system) and
radios. They should IMO be handled as two distinct checks to avoid missing things.
So for Instruments additional considerations
1) AI: yes check for erect and stable but also note on your walk around what the resting attitude of the aircraft is. Most little Cessna's and Piper's sit on the ground at 2 to 3 degrees nose up. The horizon bar should reflect this. Also if the aircraft is sitting on level ground the roll index (the little orange marker at the top of the instrument) should be exactly at zero bank. When the AI's get old, or are carelessly mounted out of level then you get a permanent bank error. Unnoticed this can be disconcerting as the aircraft will start to turn every time you level the wings.
2) DG: comparing the mag compass is not much help if the compass is off which in my experience is pretty common. So a parallel taxiway is a good double check and of course the line up check will give you a last chance to make sure the DI is properly set.
3) The Turn Coordinator. When you first turn on the master as part of the walk around listen for the sound of the instrument spinning up. No noise means the instrument is U/S so you find out right away. If it is making nasty grinding noises then you probably do not want to fly actual IMC as it is the only thing keeping you alive if the vacuum system fails.
4) ASI, ALT, ROC. I think these checks have been adequately covered in previous posts
Flight Instrument Systems. That is the systems that power/affect flight instruments. These are the vacuum system, electrical system and the alternate static source. IMO this is one area where flight schools do not generally do a good job. Things to check are as follows
5) Vacuum system. The AI and DG only work if they get vacuum air at the right pressure. Checking that the suction gauge is reading the right value is a vital pretakeoff and regular inflight check. It is important to note that too much suction is almost as bad as too little.
6) Electrical system. Your average club trainer has no electrical system redundancy so every part of the system has to be healthy. In particular
the battery should be at or near full charge before taking off in IMC conditions. If the battery is showing a high rate of charge on the ammeter than you should wait on the ground until the charge rate has dropper to normal before taking off. It the charge rate does not come down than you should not takeoff. Also obviously, any indication that the charging system is not charging (ie a negative value on the ammeter) would also be a no go item.
7) alternate air: Make sure you know where the control is, that it actually moves and that it is in the normal position
Radios:
8) A full VOR check is
- a clear ident is heard
- needle centered from with the radial cross checked to your geographic
- needle full deflection both ways with a 10 deg OBS change
- to/from flag flips at 90 deg to the radial you first centred the needle
- to flag with needle centered with OBS turned 180 deg
- No more than 4 deg needle split between two VORs with the same OBS value.
- The localizer and glideslope is not checked when you check the VOR so if available tune and identify the approach aid and make sure the needle deflections are sensible ( ie GS up and loc needle in the direction of the runway centerline).
9) ADF: A full ADF check is:
- Select "Ant" and listen for a clear and relatively static free ident and needle parked pointing at left or right wing tip
- Select ADF for a station ahead of the aircraft and needle moves to bearing and steadies
- repeat for a station behind you
(Note if there are no nearby aeronautical stations a commercial AM radio station works as well although the needle will usually not be a steady)
10) Comms:
- start by using the test switch to break the squelch and then set the volumes
- comm check both radios.
11) Transponder:
- check the response light (ie the little orange or green light that blinks every time the transponder is interrogated) illuminates when the transponder is switched to the test position
12) GPS: (Non IFR approved system)
- Observe system test pages, data base validity date and verify flight plan waypoints, if loaded in flight plan page