Hi Tim and Al, Perhaps it was just a pressure pulse which blew the cover
off. If you attatch a rear-facing duct you are likely to produce a
negative pressure difference, and an altimeter with an inboard static vent
would read higher than you are.

Perhaps the best initial solution would be to drill a 10-15mm hole in the
access cover, (or anywhere else really.) which depending upon the airflow,
would act as a static vent... neither increasing or decreasing the ambient
pressure.

I wonder if the pressure pulse was created by the closing of the u/c
doors, or because you where using the screen ventilation system, which
admits air onto the screen... Where is that supposed to go ?

Pete

At 06:14 06 September 2009, Tim Taylor wrote:
On Sep 5, 11:08=A0pm, Al wrote:
On Sep 5, 10:03=A0am, Tim Taylor wrote:

After all the threads on venting high pressure air overboard I
though=
t
I would share this one with you.

I sealed up the ASW17 canopy and its nice and quiet now.
On Tow yesterday as I retracted the gear the pressure change was
enough to blow the hatch off the top of the turtle deck.