Mailing List lml@lancaironline.net Message #67808
From: Mark Sletten <mwsletten@gmail.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Legacy Canopy - Follow-up
Date: Tue, 05 Nov 2013 16:55:47 -0500
To: <lml@lancaironline.net>
Erik,

Regarding your most recent post:

One poster went so far as to equate it to nothing more than forgetting to turn on your transponder after take off because it "probably happens all the time" and is an "event not worth discussing".

First, I did not say it "probably happens all the time." I do not, in fact, have any data (other than anecdote) on the frequency of such occurrences. Meaningful discussion will not be possible if we put words in each other's mouths.

Second, if you inferred from my post that I believe an open canopy that interferes with aircraft control is the equivalent of forgetting to turn on the transponder then I wasn't clear. That's NOT what I meant. What I meant is you likely haven't heard reports of uneventful open canopy incidents because if such an occurrence truly IS uneventful (i.e. it caused no problems with aircraft control) the pilot will likely not bother to report it, precisely because it was a nonevent. In that case, it would be much like forgetting any other non-critical checklist item, such as taking off with the transponder in standby.

We have yet to establish definitively there is a problem here that needs a solution. I'm hesitant to accept anecdote over the kit manufacturer's word. Human perceptions are far from perfect in the best of circumstances. Add a bit of emergency-induced adrenaline to the mix and perception/recollection can get very fuzzy indeed.

Here are a couple of old posts to the LML I was able to dredge up. First is from Charley Brown regarding an incident where the latch mechanism on one side of his canopy failed in-flight. This suggests it's possible for the Legacy canopy to open in-flight even if properly latched before take-off. It's not entirely clear from the post whether this incident was caused by poor design or incorrect build.


This second is from Dennis Johnson who claims first-hand knowledge of at least one Legacy pilot who successfully and safely flew his aircraft with the canopy open. Dennis also says he's had numerous discussions with other Legacy pilots and believes these occurrences are common.


There are many, many things we could possibly do to mitigate poor checklist discipline, but everything involves trade-offs. For my own part, I would be leery about adding complexity with a secondary latching system, especially when a warning light is fairly easy to implement (a quick search of the LML yields many ideas). I agree that a canopy open light doesn't prevent takeoff with the canopy open, but a failure of the light wouldn't further compromise safety. I would urge we first determine there is a problem worth seeking a solution for before introducing complexity and unknown failure modes to something critical like our only emergency egress route.

Respectfully,

--Mark




On Tue, Nov 5, 2013 at 12:13 PM, Erik Larson <asw20747@aol.com> wrote:
I appreciate the continued discussion of the Legacy Canopy issue.... some don't think it's a big deal.... others, including myself, still think it IS!!!

One poster went so far as to equate it to nothing more than forgetting to turn on your transponder after take off because it "probably happens all the time" and is an "event not worth discussing".

In that regard, could anyone come forward and state, unequivocally, that they have taken off in a Lancair Legacy (not 230/320/360) with the canopy unlatched and had it be a "non-event".... ANYONE?

Other's have said it's just a simple matter of judicious use of checklists......but this canopy issue is, IMHO, a "perfect storm".  You will methodically go through your checklist in the run-up area....checking and re-checking everything (controls, fuel, trim, etc.)....all the while the canopy is cracked OPEN for ventilation.  You are holding short of the runway (canopy still cracked) and then on that one fateful day you are cleared for "Immediate Takeoff".... you perhaps have a "below the line" checklist or flow pattern but you're tired or it gets rushed and you forget the canopy - LOCKED.  Perhaps unlike anything else in the Legacy...there is NO going back ....no second chance to correct your mistake ..... you are along for the ride....and from everything I've read..... it's NOT going to be fun. (see below)

As Mike Larkin mentioned, the Airbus does have a fairly sophisticated takeoff warning system that backs up two well trained pilots with strict use of checklists and yet STILL monitors 5 "must have" items for takeoff, as a backup, because there is simply NO second chance with missing any those items.

I still maintain that some fairly simple backup canopy latch, like is employed on the the Vari-eze, Long-eze or Cozy might be the answer vs. a fairly complicated micro-switch or switches, tied to the canopy locking mechanism......with an audio AND visual warning that hopefully triggers when a set ground speed or airspeed is met.

If you don't think it can.... "happen to you"..... because you ALWAYS use a checklist and are a VERY good pilot with VERY disciplined procedures.....
please......think again and...... best of luck!!!


Regards,

Erik Larson
Legacy / N74FX 

On Sep 19, 2013, at 8:22 PM, Gary Weeks <g.weeks550@gmail.com> wrote:

Many thanks Bill for sharing that first hand account of an unlatched canopy.

My comment was a reflection of what I had been told or had read somewhere previously (not from actual experience) and I am happy to be corrected, especially from those who have been there and done that.

Yes we need to carefully check the canopy is latched before takeoff. Thanks again.

Gary

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Sent from my iPad

On 19/09/2013, at 11:41 PM, "Bill Bradburry" <bbradburry@bellsouth.net> wrote:

I am sorry, Gary, but I have to disagree with that third sentence.  The Legacy can NOT be flown safely with the canopy unlatched!  If you take off with the canopy unlatched, you MAY survive…I did!  You MAY not damage the plane…I did!  Several others have not survived.  It is a harrowing experience!  I now check the canopy latch several times before each takeoff!
 
When the canopy is closed it takes a little extra force to move it up off the canopy seal, then it is easier to raise and you have the gas struts helping you.  So at about 60 knots, the canopy will suddenly pop up and go all the way or nearly to the stops.  This action blanks off the elevator and you lose pitch control.  The canopy then is blown back down and you temporarily regain pitch control before it is sucked back up for another round.  By the time it is headed back up the second time, you had better have the power off and using that short instance of pitch control to get the plane either on the ground or close enough for a hard landing.  If this happened at 100 feet or so, flowers would be in order.
 
It is possible that you could unlatch the canopy at cruise speed and it would only open a few inches, but when you tried to land, the lack of prop blast would put you back into this regime.  I don’t recommend trying any of it.  Latch the damn canopy!
 
Bill B


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Example of other systems on other airplanes that will kill you if you don't follow some form of checklist: Leaving the fuel selector in the off position prior to takeoff or not trimming the airplane prior to takeoff.  The very first airplane accident I ever witnessed was the former.  The club had a rule to turn off the fuel when finished.  This particular type would allow you to taxi all the way to the runway and get to about 100 feet before the engine would quit.  Secondly example, If you don't put the trim in the proper place on an Airbus it will not fly, we use "checklist, bells and whistles" to prevent an error here.  Bottom line, if your careless, it can kill you...  Use a checklist, dummy light, warning system of some sort.  You"ll live longer and be able to tell your stories over beers form many years.

Mike Larkin...

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I strongly suspect the reason we don't hear about incidents where an open canopy didn't interfere with controllability is because it's not really an event worth discussing, plus there's an element of embarrassment. 

"Hey guys, I forgot to close my canopy before take-off and had to come back to land before I could finish my trip."

Don't really hear too many stories about people forgetting to turn on the transponder either.

"Hey guys, I forgot turn on the transponder before takeoff. ATC reminded me, so I turned it on."



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