Rear Door departs a DA40 after takeoff

[Rich]

I don’t know at what point Diamond started using gas springs in the latches. Mine are coiled spring steel and have been trouble-free.

But another thing that could theoretically happen, say after working on the latch for some reason, would be for the locking rods to not properly engage. Early on in ownership I had this problem with the right side canopy rod and it popped loose a couple of times in flight. Nothing untoward happened otherwise. I cobbled a temporary fix and Diamond subsequently corrected the problem.

[chili4way]

The AFM specifically states the rear door is to be unlocked in flight. It’s emergency egress. And it would be totally irresponsible if you have rear seat passengers. There is no way to unlock it from inside.

The current production DA40NG (and presumably DA40) canopy and door latches can be opened from the inside if they are locked. The reason for mandating that these be unlocked in flight is that the canopy and door cannot be opened from the outside (by rescue) if they are locked.

[Rich]

The AFM specifically states the rear door is to be unlocked in flight. It’s emergency egress. And it would be totally irresponsible if you have rear seat passengers. There is no way to unlock it from inside.

The current production DA40NG (and presumably DA40) canopy and door latches can be opened from the inside if they are locked. The reason for mandating that these be unlocked in flight is that the canopy and door cannot be opened from the outside (by rescue) if they are locked.

I will conditionally stand corrected. I have a different operating mechanism, so I'll doublecheck the next time I'm at the airport.

However, if locking the door does not prevent it from being opened from the inside, this would mean that locking the door does not really prevent unlatching. Therefore it is no assurance against the latch disengaging in flight.

[mhoran]

I've tried to show how the lock mechanism and emergency latch works from the inside. When you pull on the inner bit of the latch (not the larger lever), it slides a bit of metal on the back side of the lever forward. This disengages the bit of metal that hooks behind the lock mechanism, allowing the door to open from the inside in the event that the door is locked from the outside.

If the door is locked, this would prevent the lever from vibrating opening on its own, in the event of over-center gas strut failure. The emergency latch is spring loaded to keep the lock hook (for lack of a better word) engaged. Of course, it would also prevent emergency access from the outside, hence the prohibition from locking the doors while in flight.

The over-center gas strut is really a terrible design. I don't understand why they changed from the original spring. The gas strut in my experience only lasts a couple years of regular usage before it wears out, and takes hours to replace.

[Steve]

Matt: Yours is a completely different latch design than the one that Rich and I have on our airplanes (even forgetting about the spring vs gas cylinder design change). I like the old, dependable design - mine is 23 years old and no maintenance has been required (other than lubricating the rear hatch pushbutton occasionally). Mine won't open from the inside or outside with the lock engaged (although I believe that the lock engagement plate on the mechanism is designed to pull free with enough force applied (like a fire starting in the cabin to motivate your adrenalin surge). I don't know for sure, and I don't want to have to test it...

[CFIDave]

I'm guessing there have been more than a dozen DA40 doors opening and departing the aircraft in flight, including during takeoff when detached doors have been recovered on the runway.

Years ago, I had an occasion when the rear door of my 2008 DA40 XLS unexpectedly came open in cruise flight, and was kept from opening all the way (and departing the aircraft) only by the red safety latch. We knew not to try closing it in flight, so we landed and re-closed the door on the ground. It never happened again.

[Steve]

Shortly after I bought my DA40 (must have been 2002 or 2003), I flew over to Houston (KEFD) to do some work with NASA (talk about a rush for a child of the Space Age - flying your own airplane, parking next to the NASA T38s, and working with NASA engineers and some of the astronauts). At any rate, I met a fellow DA40 owner down there (there weren't many of us in 2002-3). He lost his rear hatch on the runway during takeoff. He was a student pilot at the time, and neither he, nor his Flight Instructor noticed that the rear hatch was wide open for the engine start, taxi, runup, and takeoff roll. Luckily, he recovered the hatch (which was undamaged except for the hinges).

[dmloftus]

If a rear door completely detaches, does that mean the top hinge pin has bent/snapped or has it somehow worked loose to allow the door depart the aircraft? I’m curious how someone would simply reattach. Seems there must be some type of mechanical damage.

[Steve]

The carbon fiber hinge pieces attached to the hatch fracture. The portions remaining within the hatch must be routed out and then new ones epoxied in.

[alanhawse]

Max Trescott talked about this event in his podcast today... (or most recent)... he says that he is aware of >17 events of this happening.

The one thing he said which I had not heard/read was that trying to close the door latch in flight might actually have the opposite effect... and cause the door to go flying off because the pin could force the door open.

Regardless... I have check the door latch on my checklist 2x times...