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Finally, after covid I've started working on my instrument rating in my DA40 NG. In doing partial panel training, one of the topics that has come up is how best to practice an approach. Just dimming the PFD loses the HSI and glide slope. Is there a better way? I think the most common failure on an actual approach would be to lose the AHRS but not sure how to simulate that.

I suggest finding an FAA approved simulator with a G1000. Your instructor can throw random failures/scenarios that should manifest accurately on screen.

I second the recommendation for a simulator, which is where I did almost all my G1000 failure work. My CFII also hit the reversion button a few times or would cover the MFD with her clipboard. When the DPE got in the plane for the IFR check ride I walked him through a bunch of G1000 features and he said, "I'm familiar with it. We're not going to do any partial panel work because you have so much redundancy in this plane I don't believe it will ever happen."

He also had done Angelina Jolie's IFR check ride in her Cirrus, but I don't know if he allowed her the same gimme.

My DPE turned off my PFD (dimmed it to zero) but did not allow me to use the reversion button. He then had me fly a non-precision approach using the backup instruments and the magenta line.

On one hand this could be thought of as a pretty odd way to simulate failure, since it's not reflective of how (I suspect) most real-life failures would happen. In fact, my actual real-world G1000 failure so far was a magnetometer failure — which resulted in no more heading, and thus no more autopilot modes other than ROL, and no traffic info, and no wind info. However, the DPE did research this quite a bit, and chose that mode of failure specifically because it left me with very few instruments, and gave me the bare minimum I could possibly have and still fly an approach.

In bygone days partial panel was almost always one of two things: Simulating loss of vacuum pump or of the attitude indicator itself. Either of these scenarios was a big deal in IMC and not unlikely. For us (even us steam-guagers) the vacuum pump scenario is out the window. Individual instrument failure of one type or another is about it. "Clean" alternator failure isn't an immediate problem. I've determined I can run normal daytime full load on the battery for over an hour. Total loss of electrical system (unidentified smoke in cabin, e.e.) would likely be the worst scenario. For that I have at least limited navigation and control capability via iPad/FF/Stratus enough to outlast fuel in the tanks. That last scenario is worth practicing with. Something I haven't yet done.

My one real G1000 failure was AHRS and I didn't realize it. I am not sure how it would have affected an instrument approach. I wasn't IMC but it was at night and I treat moonless nights as IMC, so I was mostly on instruments.

The rating allows up to 20 of the required 40hrs in a simulator and I agree with the recommendations to do at least 20 in the sim. It's much less expensive and much more productive.

WRT how to fail, there is a lot of variation in how CFIIs and DPEs simulate partial panel, none of which simulate what your panel is likely to look like in the real world.

Your CFII will most likely have their preferred method. Finding someone else who took a check ride from the DPE you expect to use is the best way to find out how that DPE does the test.

If they take away the CDI, you should probably go missed. Whether RNAV, ILS or VOR, without the CDI, you have no lateral guidance. XTK might work for an RNAV, but you'd probably be better off with a pseudo precision radar approach and get vectors from the tower. I don't recall how my DPE did the partial panel, which I think speaks to how it was a not a big deal.

I think the most important thing to keep in mind with DPEs is that you are still PIC. You can make whatever decision you think is necessary for safe completion of the flight; even if the flight is simulated. You are note a slave to the DPE.

Regardless of what contrived scenario a DPE or CFII may concoct it's a worthwhile exercise to understand how you would deal with various realistic failure scenarios. In my case, the installation of the Aspen did introduce a possible simultaneous failure of attitude indicator and HSI - much like the loss of a vacuum pump in olden days. Loss of the former is generally considered the most problematic, especially if it's a bit turbulent. But consider that ROL mode in the AP should still be available for loss of AI. Do not dismiss the value of this. In my case I also have alternative AHRS and synthetic vision in the form of 2-3 different iPad/iPhone displays each driven by potentially two different GPS/attitude sources not dependent on the Aspen.

Loss of the CDI in the Aspen is a pain but my 430W has its own CDI so I could still fly an ILS, RNAV (including LPV) or whatever, though it'd be essentially hand-flown, in whole or in part.

Boatguy wrote: ↑Wed Jul 21, 2021 5:10 pm The rating allows up to 20 of the required 40hrs in a simulator and I agree with the recommendations to do at least 20 in the sim. It's much less expensive and much more productive.

Agree with this with the one caveat that if your training area's weather offers a lot of opportunities for actual IMC, take advantage of it. Neither the sim nor a hood or foggles do as good a job of offering exposure to disorientation as actual does.

I count myself very lucky to have found flyable IMC in Denver in March (albeit 1-3 degrees C) when I trained.

good luck,
dan