I think I have the doubtful accolade of the most door departures on one
Europa (3!)
There are several other known occurrences - some before and some after the
mod. which added tubes to the bolt holes.
My own experience is as follows:
1) Pilot's door departed on first flight at 200ft. in the climb out. Pilot
was "sure" it was closed properly but photo shows rear bolt was in fact out.
2) Fitted four switches (as described back in 97) where front switches (in
series) bring the back switches "live" to headrest mounted beeper. This has
the advantage that you can work on the plane with one or more door open and
electrics ON without the beeper going off. Lost door in climb in spite of
this system due to having adopted thumping rear part of door during checks to
ensure it was closed. Door was too fragile for this treatment and the surround
cracked unseen with inevitable result. Now redux filled in this area.
3) Unlatched the door to avoid asphyxia on a hot day at the holding point.
Forgot to close it and door lifted during take-off run. Just an aborted take-
off this time. This clearly demonstrates the aerodynamic force building up on
the door. With both latches undone I doubt if you could be airborne before it
lifts, so this is the least troublesome scenario.
So
YES the doors WILL depart.
and IMHO
YES you need switches, but on doors alone
NO, a system relying on one switch closing/opening before another is difficult
to set up and maintain (in comparison with a go/no go system).
NO a horn is not sufficient unless it can be heard in headphones.
YES a tone into the headphones is best, (assuming you don't fly without them,
though same system will work into a cabin speaker. But your Europa has better
insulation than mine it you can use it with the engine running !)
If you have the knowhow, make up a pcb with a clutch off 556's which generate
modulated tone streams. You can then expand your audible warnings to include
U/C, (more important even than doors), stall speed , temperatures etc. etc.
I say modulated tone streams advisedly, as continuous tones in isolation are
difficult to identify when you you have more than two, and need to know in a
hurry which one is going off. Better still with a pc on board, you can
arrange to be shouted at !
Graham C. G-EMIN
<<the rear bolt is the only one that is difficult to
ensure engaged properly>>
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