Back door departing the airplane

[BritInNC]

I should be doing my PPL checkride about now.

On Wednesday evening I planned to take my final pre-checkride flight to tighten up my short field landings. Pre flight was normal, as far as I can remember I latched the back door. Started the engine with the front canopy open and closed it once we had the AC on. No door warning light. Taxied to the ramp for runup and completed that with no incident and no warnings. Did not notice anything unusual. Normal takeoff, however, after a few seconds I noticed increased noise and my CFI in the right seat said that he thought the back door may have opened. Before we had much chance to react the secondary latch on the back door failed, the door opened completely and soon after departed the airplane. It didn't hit anything. No door warning light even though the door was no longer on the plane. We had plenty of runway to land and did so. Airport operations retrieved the door and I'm in the process of getting a ferry permit to get it to the AME who thinks they can repair it (apparently a better approach than replacing it as replacement doors often do not fit well). I am obviously concerned that the door warning system appeared to fail here, as well as the fact that the secondary latch on the back door failed almost immediately.

I guess this is a PSA. Check and double check your back door latch, don't assume that the door warning light will save you from such forgetfulness. I'm interested in other's thought on this, Diamond did pick up the accident report and has reached out for more information, I will report back if this turns out to be anything more than presumed pilot error. My new approach will be to lock the back door every time I close it (I wouldn't do this when I closed it to pull the plane out of the hanger as I knew I would open it again), and make sure the latch is flush in case this was a situation where I almost closed it but not completely (although the door warning light should have come on at some point).

And I just saw that my engine is in the MSB-E4-043 list. Good times.

[jwx96]

I treat the rear door the same way that you do now. Every time I close the backdoor I lock it and make sure that the handle is flush. I'm glad it turned out well. I also check the tips of the latching pins. Someone previously posted that their canopy locking pins came loose prevented them from opening the canopy. They were trapped inside. Do you mean that you're going to get a ferry permit to fly the plane without the rear door?

[BritInNC]

Glenn at SouthTec has seen this before and after inspecting the photos said to relatch the door and duct tape all around it. The frame was undamaged so it’ll be very secure but requires a special permit for the ferry. I have a video but not sure how to post it.

[blsewardjr]

FYI- The DA40-180 AFM in Section 2.16.5 states that

2.16.5 DOOR LOCKING DEVICE
The canopy and the passenger door must not be blocked by the door locking device during
operation of the airplane.

[BritInNC]

Realized my last post was a little short and may have sounded snarky so wanted to respond better now I have time.

I was aware of this requirement which also concerned me about the ferry flight. The door is not actually locked so it doesn’t break this requirement, but taping over the latch to ensure it doesn’t open is probably in the same spirit. The way I look at it the door is secured to the frame using the regular latches and is taped to the frame so in an emergency you just kick it out from the inside and I think you’d even be able to unlatch it with enough force. The special flight permit was required by the FSDO when they called about the incident and may be related to this or the general airworthiness of the plane.

It hasn’t been approved yet so I guess we may not get it. At that point I guess I’ll drive the door to them and then they’ll have to send a mechanic to install it at the hanger. I’ll let everyone know if it gets more complex than that.

[CFIDave]

Diamond Austria recently (8/22/2024) published a Service Information document "Closing and latching the passenger door" for the DA42, that would seem to also be directly relevant to DA40s, since the rear door design is the same:

[BritInNC]

I agree. Someone sent that to me yesterday as well. Maybe this is why Diamond reached out to me yesterday.

According to Glenn at SouthTec he has not heard of a door coming off and striking the plane in a DA40, but on a DA42 it has a tendency to hit the right engine area. That is maybe why this is focused on the DA42.

I was surprised how easily and quickly this happened in my case. Given how catastrophic this could be I would hope I could rely on the door warning light or the secondary latch to keep it closed for longer while you tried to land. I would estimate that the time between us noticing the door was unlatched and the door ripping off was 5-10 seconds. Even if I somehow removed the warning (I am certain we never got one in this case), it should come on again whenever the power is over a certain level which would have reminded me on taxi and run up, or even earlier in takeoff. Maybe I’m expecting too much of the systems though and this comes down to good old checklists and double checking before you close the front canopy.

[Rich]

One thing you should check from time to time is that the door warning light is actually working. It wasn't this one but one of the bulbs in my warning panel burned out some years ago and had to be replaced.

Another is that the latch spring is actually working properly: With the rear door open open and close the latch. You should feel the latch pulled into the closed position as it goes over center. The gas spring Diamond has gone to is subject to failing.

[BritInNC]

All good points. My door warning is part of the g1000 nxi system so no bulbs there. We also checked the system when we were back on the ground using a key to push in the back canopy latch and it all worked fine so still don’t know what occurred this particular time.

With the latch I’d prefer if there was a tactile ‘click’ when it was closed rather than the soft close as it is possible to think you closed it when it’s still slightly sticking out.

[Paul]

Nice job on aborting the takeoff and not making the situation any worse.