Mailing List lml@lancaironline.net Message #50383
From: David Standish <carbonflier@bresnan.net>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Legacy Canopy Down & Latched Indication
Date: Tue, 10 Feb 2009 00:50:05 -0500
To: <lml@lancaironline.net>
Valin & Allyson Thorn wrote:

Hey Legacy pilots and builders,

There have now been two Legacy crashes, including the loss of a fellow pilot, apparently from canopy openings on takeoff. I’m sure we’d all recognized even before these losses that the standard Legacy canopy latching system can easily mislead a pilot that it is closed but not be latched down. And, with these great visibility bubble canopies, but hot green house effects, the canopies are usually propped open on the ground and not closed and latched until just before takeoff. This makes it fairly likely that every Legacy pilot at some time, with fatigue or distractions, may not latch the canopy down before takeoff…

Given this probability of occurrence, we’ve been planning to use simple micro or proximity switches on both the canopy and the latch mechanism to control an indicator/light on our instrument panel as a secondary and hard to miss canopy configuration indicator. It would be red whenever the canopy is not down OR not latched. I haven’t yet decided if it would be good to have it green when the canopy is down and latched.

Anyway, I just wanted to share this with other pilots and builders that are thinking about how to mitigate this in flight canopy opening risk after the second accident from this (apparent) root cause. This kind of set up should be a very easy retrofit for flying Legacy airplanes, too.

Valin Thorn

Legacy

Houston, TX USA

http://www.starflight.aero/legacy/

P.S. Also, if you do the mod we worked up a few years ago that props the canopy open when you unlatch the canopy (so you can get your fingers under it to open it) you get another more clear indication that the canopy is not latched… Don Barnes has this info on his website:

http://www.lancairlegacy.com/tips_canopy_fixes.html

On the door of my IV a contactor closes when the door is in the closed position a micro switch detects the door latch position so that the circuit is complete when the door is properly closed and latched. This circuit powers a micro relay that opens when the door circuit is complete and closes when the door is open or unlatched. The relay in turn powers a red annunciator light near the middle of my scan on the panel near the gear lights. This would probably work great on the Legacy canopy.

David
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