Mounting Stuff on the Canopy or Glare Screen - Safe?

I am in the midst of an instrument panel refit on a Standard Cirrus that will include a PowerFLARM core. The mount of the FLARM antennas is always a lifely subject here on RAS. I have read and absorbed the very instructive FLARM antenna placement application note.

Anyway, someone mentioned to me years ago that it is a bad idea to mount things on the canopy or canopy rails (PDA, Camera, etc) as it could prevent full ejection of the canopy and leave it tethered to the fuselage by a power or control cable. This could make a bad situation worse (take that statement for what it is worth). Truth or myth?

Assuming for the moment that the above is true, then same logic leads me to the bad idea of mounting things onto a glare screen that is attached to the canopy like with a Standard Cirrus. If mounting things on the canopy is bad, then mounting things on a canopy attached glare screen is also bad.

This finally leads me to how to mount FLARM antennas. Often FLARM antennas are mounted onto the glare screen. But two FLARM antenna coaxes would definitely be stong enoght to tether the canopy, back to bad again. An optional placement of the antenna would be below, but not attached to, the glare screen. However this might impact coverage.

What are your wise opinions?

Great question and one that many pilots are in denial about.
Your Standard Cirrus probably has no carbon fiber in the cockpit.
I have an LS-8 and mounted both Flarm antennas under the glare shield. They work perfectly.

At 22:11 10 February 2016,
wrote:
Great question and one that many pilots
are in denial about.
Your Standard Cirrus probably has no
carbon fiber in the cockpit.
I have an LS-8 and mounted both Flarm
antennas under the glare shield.
They work perfectly.

In my previous 20 I mounted Flarm and
xpdr antennae in the nose cone ahead of
the rudder pedals. Use 80 grit sandpaper
to shape ½ x 2" balsa from your local RC
hobby shop.

In my 27 I have my Flarm antennae
coming through a hole in my glareshield
on a little balsa mast.

Still scheming on the xpdr antenna.

On Wednesday, February 10, 2016 at 5:04:33 PM UTC-5, Six-Seven Romeo wrote:
I am in the midst of an instrument panel refit on a Standard Cirrus that
will include a PowerFLARM core.

Good for you! Glad to see the turds posting mis-information on RAS ignored ;-)

The mount of the FLARM antennas is always a lifely subject here on RAS.
I have read and absorbed the very instructive
FLARM antenna placement application note.

Anyway, someone mentioned to me years ago that it is a bad idea to mount
things on the canopy or canopy rails (PDA, Camera, etc) as it could prevent
full ejection of the canopy and leave it tethered to the fuselage by a power
or control cable. This could make a bad situation worse (take that statement
for what it is worth). Truth or myth?

Truth, implicated in at least one fatality (PDA mount prevented canopy jettison).

Assuming for the moment that the above is true, then same logic leads me
to the bad idea of mounting things onto a glare screen that is attached to
the canopy like with a Standard Cirrus.

Yes, but: you can cut a hole in the glare shield and mount the antenna
on a light-weight support below, poking through the hole. Presto, canopy
can jettison freely, and you can easily remove canopy without deranging
antenna. IIRC there are examples in the FLARM note.

Hope that helps,
Best Regards, Dave

Dave, wow - what timing!

On 2/10/2016 3:32 PM, Dave Nadler wrote:
Snip...

Anyway, someone mentioned to me years ago that it is a bad idea to mount
things on the canopy or canopy rails (PDA, Camera, etc) as it could
prevent full ejection of the canopy and leave it tethered to the fuselage
by a power or control cable. This could make a bad situation worse (take
that statement for what it is worth). Truth or myth?

Truth, implicated in at least one fatality (PDA mount prevented canopy
jettison).

Having just spent most of the day extracting info related to every 2000-2015
glider-based fatality from the NTSB database (and, yeah, I'm pretty familiar
with how much crunch-related info can manage to never make it into their
reports and conclusions), I'm curious as to year and country of the above
fatality. It doesn't seem to ring a mental bell from my day's work.

Thanks!
Bob W.

On Wed, 10 Feb 2016 16:27:09 -0700, BobW wrote:

Dave, wow - what timing!

On 2/10/2016 3:32 PM, Dave Nadler wrote:
Snip...

Anyway, someone mentioned to me years ago that it is a bad idea to
mount things on the canopy or canopy rails (PDA, Camera, etc) as it
could prevent full ejection of the canopy and leave it tethered to the
fuselage by a power or control cable. This could make a bad situation
worse (take that statement for what it is worth). Truth or myth?

Truth, implicated in at least one fatality (PDA mount prevented canopy
jettison).

Having just spent most of the day extracting info related to every
2000-2015 glider-based fatality from the NTSB database (and, yeah, I'm
pretty familiar with how much crunch-related info can manage to never
make it into their reports and conclusions), I'm curious as to year and
country of the above fatality. It doesn't seem to ring a mental bell
from my day's work.

There was a mid-air in the UK (Yorkshire) in 2006. One pilot got out, the
other didn't. http://news.bbc.co.uk/1/hi/england/6158561.stm

The AAIB report said that latter had electronics mounted on his glare
shield and canopy frame, cables secured with cable ties. The ASW-19B, hit
the ground with part of the canopy still attached. The front jettison
lock had been released, rear locking pins still locked.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On 2/10/2016 5:07 PM, Martin Gregorie wrote:
On Wed, 10 Feb 2016 16:27:09 -0700, BobW wrote:

Dave, wow - what timing!

On 2/10/2016 3:32 PM, Dave Nadler wrote:
Snip...

Anyway, someone mentioned to me years ago that it is a bad idea to
mount things on the canopy or canopy rails (PDA, Camera, etc) as it
could prevent full ejection of the canopy and leave it tethered to the
fuselage by a power or control cable. This could make a bad situation
worse (take that statement for what it is worth). Truth or myth?

Truth, implicated in at least one fatality (PDA mount prevented canopy
jettison).

Having just spent most of the day extracting info related to every
2000-2015 glider-based fatality from the NTSB database (and, yeah, I'm
pretty familiar with how much crunch-related info can manage to never
make it into their reports and conclusions), I'm curious as to year and
country of the above fatality. It doesn't seem to ring a mental bell
from my day's work.

There was a mid-air in the UK (Yorkshire) in 2006. One pilot got out, the
other didn't. http://news.bbc.co.uk/1/hi/england/6158561.stm

The AAIB report said that latter had electronics mounted on his glare
shield and canopy frame, cables secured with cable ties. The ASW-19B, hit
the ground with part of the canopy still attached. The front jettison
lock had been released, rear locking pins still locked.


Ah, so - that would appear to qualify in my book. Thanks, Martin. If : 1) the
Beeb is accurate, and 2) I've understood them correctly, it would appear the
(rear-raising via strut under normal conditions?) canopy had its
front/emergency release pulled, but not the rear, *and* the front end was
restrained to "some extent" by cabling? (That's not to wonder if the pilot
simply ran out of time - for whatever reason - to operate the aft latch[es?].)
I got the bit about the AAIB speculation, though what, precisely, I should
infer is unclear. Would it have been 100% necessary to "go through the canopy"
due to the degree of front-end restraint, or would the degree "only" have
hindered the amount the front end could raise before coming up against the
wiring, thus (possibly) resulting in a partially-raised canopy, if the strut
could overcome airloading?

In any event, any degree of hard-cabling between airframe/instruments and
ejection-desired-canopy certainly seems a bad idea to me!

As always, the devil is in the details...

Bob W.

On Wednesday, February 10, 2016 at 7:10:55 PM UTC-5, Martin Gregorie wrote:
On Wed, 10 Feb 2016 16:27:09 -0700, BobW wrote:

Dave, wow - what timing!

On 2/10/2016 3:32 PM, Dave Nadler wrote:
Snip...

Anyway, someone mentioned to me years ago that it is a bad idea to
mount things on the canopy or canopy rails (PDA, Camera, etc) as it
could prevent full ejection of the canopy and leave it tethered to the
fuselage by a power or control cable. This could make a bad situation
worse (take that statement for what it is worth). Truth or myth?

Truth, implicated in at least one fatality (PDA mount prevented canopy
jettison).

Having just spent most of the day extracting info related to every
2000-2015 glider-based fatality from the NTSB database (and, yeah, I'm
pretty familiar with how much crunch-related info can manage to never
make it into their reports and conclusions), I'm curious as to year and
country of the above fatality. It doesn't seem to ring a mental bell
from my day's work.

There was a mid-air in the UK (Yorkshire) in 2006. One pilot got out, the
other didn't. http://news.bbc.co.uk/1/hi/england/6158561.stm

The AAIB report said that latter had electronics mounted on his glare
shield and canopy frame, cables secured with cable ties. The ASW-19B, hit
the ground with part of the canopy still attached. The front jettison
lock had been released, rear locking pins still locked.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Thanks Martin, that's the accident I was remembering but I didn't
have the detail at hand...
Best Regards, Dave

I noticed on page 4 of the aforementioned PowerFLARM Antenna Application Note (lots of great pictures of how to do, and not do, things) the following;

"Ensure that the installation does not conflict with any operation of the aircraft e.g. Canopy emergency release. No, the coaxial antenna cable will not 'just rip'..."

Which implies that they too know that mounting stuff on the canopy is bad.

This finally leads me to how to mount FLARM antennas. Often FLARM antennas are mounted onto the glare screen. But two FLARM antenna coaxes would definitely be stong enoght to tether the canopy, back to bad again. An optional placement of the antenna would be below, but not attached to, the glare screen. However this might impact coverage.

What are your wise opinions?

As Guy suggests, if your Std Cirrus is anything like ours (#446) there is no carbon anywhere, so all of our antennas (GPS, FLARM, transponder) are mounted underneath the glare shield. GPS patch antennas are simply strapped on top of convenient instrument cases, the FLARM antennas have a quick and dirty plywood mount that is attached to the rear of the transponder (the deepest of the instrument cases), if I remember correctly. All work fine.

Marc