Rear Door Integrity

[perossichi]

My pre takeoff flow check starts in the rear. Rear door closed and latched. Canopy secure. Trim t/o. ... moving forward to the right of instrument panel and continuing to the left.

The manual says if the rear door is not latched, the door is being held down by the safety catch. Do not attempt to secure it.

[blsewardjr]

Same with me. I physically lightly push against the rear door and double-check the indicator prior to takeoff.

[CFIDave]

We had a rear door open in flight back when we owned a DA40. It was retained by the safety catch, but we knew enough NOT to try and re-close it in flight (releasing the safety catch would likely have caused the door to depart the aircraft).

So we landed at a nearby airport and closed the door. Never had a rear door problem again...

[Charles K]

My checkmate checklist has check rear door secure and I turn around and look - you can tell if closed and latched just by looking.

[Davestation]

Setting aside the obvious possibility that it wasn’t closed...

When the door pops open, it’s usually in the ground and I think that’s because of the extra vibration.

1. The door pin geometry could be off. I’ve had door latches that didn’t want to properly stow unless you pushed on a magic spot on the door and kept pressure on the handle. The bolts aren’t properly engaging with the guides at rest.

2. Particularly on the newer aluminum door latches (euro locks) there is a gas shock instead of a metal spring that keeps the handle over center. These wear out over time and if the handle doesn’t feel like it pulls itself closed the last 20° or so, time to replace it.

On a side note, both the old and the new latches are designed to be easily opened while locked. They say don’t lock it for flight as a precaution, but it makes little practical difference (for starters, those locks aren’t very stout anyway and I’ve replaced countless locks because someone pulled on the handle unwittingly and it just shattered). The old latches have little rubber grommets between the handle and the locking tab which allow it to bend up and over the lock cam if pulled on from the inside. The newer latches have a more elegant second spring loaded pull on the inside handle that retracts a can over the locking cam, completely bypassing it.

[Karl]

I agree with Devastation comment about the spring/gas strut.

The gas strut works as an over centre type locking mechanism. With the door open operate the the red lever. It should spring to the open and the closed position. If it does not then get the spring/gas strut changed. There is also an SB for older type locks for wear in a pin which causes the same problem.
It the gas strut/spring isn't working properly the lock can vibrate towards open during flight. This also applies to the canopy lock.

Of course this shouldn't be a problem because the back up emergency catch should hold the door but we have a potential problem here too.

The red push button can get jammed in the unlocked position if not lubricated regularly. A quick squirt of lubricant solves the problem.
I follow a routine of, Open the door latch and press the red button, open the door approx 3-4 inch. Observe the button to see if it springs back out. Allow the door to drop to the closed position, then give it a tug to check if the emergency catch has has worked. I do this twice as part of the preflight. If the button is slow to spring back or the emergency catch didn't work a quick spray of lube on the button usually resolves it.

[Rich]

The watchword for every aircraft type I've ever piloted is: "If a door pops open/loose in flight thou shalt not screw with it until you've landed and stopped."