Incident - Lancair IV-4P-T depressurises at FL250

[Ovation]

A Lancair IV-4P-T (VH-OPR) was en-route from Jandakot to Mt Gambier at FL250 when the starboard cabin window separated. Fortunately there was no damage to the airframe.

The incident occurred to the SW of Kangaroo Island and the aircraft diverted to Adelaide for a safe landing.

FlightAware track (https://flightaware.com/live/flight/VHOPR/history/20120701/2300Z/YPJT/YMTG)

[VH-XXX]

Being a homebuilt experimental it won't rate much of an event for CASA / ATSB.

[Jabawocky]

Slow news week in AD is it Ovation? :}

Got your bird back in service?:ok:

[Arnold E]

Said on a news flash that I just saw on TV that it landed on a street. Would be quite exciting if that was the case.:eek:

[Wally Mk2]

........sheez that's a looooong way to be off the coast with only one donk!!!They are damned lucky it didn't send the plane downward into the sea then Jaba it would have been much bigger news!



Wmk2

[PLovett]

They do have extensive glass areas for a pressurised aircraft. :uhoh:

[VH-XXX]

Nah Wally, surely that's gliding distance from 25,000ft.... Maybe.

[AmarokGTI]

Aircraft was "escorted" by UniSA Baron HFB (which was on its way to Kingscote) before being intercepted by RAAF PC-9 using callsign Tester05. He was offered (and took) 05 with 10kts of tailwind. Was cleared to land by Ad Appch.

[Checkboard]

The time it takes for the cabin to depressurise depends on the size of the hole, and the volume of air in the cabin.

An explosive decompression with a large window in a tiny cabin like that is no joke :uhoh:

[Jabawocky]

I am with Checkers...its no joke.

But still a slow news day for AD :E

Hay Wally, Retard Vehicle is not pressurised and will stay that way.

O2 to FL160 is about all I need to do.

[Ovation]

WMk2

........sheez that's a looooong way to be off the coast with only one donk!!!They are damned lucky it didn't send the plane downward into the sea then Jaba it would have been much bigger news!

At FL250 AND 300 Kts they would have made landfall easily without power. The FlightAware profile shows a GS after the emergency at 185 Kts. If they had to ditch at least they would have had an extra emergency exit.

It would be interesting to know whether they had (or required to have) emergency O2 on board.

[Old Akro]

They will have emergency O2 on board. The issue is that at FL280 the average useful consciousnesses is about 4 minutes. Its a salutatory experience to do the hypoxia training. While you may have useful consciousness for 4 minutes, your dexterity is pretty compromised before then.

At FL250 it won't be a lot more than 4 minutes. So, it requires some pretty decisive action. I think ordinary masks are required rather than quick donning ones. But by the time you take time to figure out what's going on, react, put on a mask, etc I can imagine it would eat up a fair bit of the useful consciousness time. It would be an experience.

[VH-XXX]

The news report stated that the occupants "of the tiny 2 seater" donned their oxygen masks to descend. The window (looks more like a door from the pics) hit the wing (not sure how that happened at 300 knots) and missed the tail.

On their way from Perth to Tasmania to catch a flight to New Zealand for a snowboarding holiday.

Photo from Channel 7.

Lucky escape after window falls from plane - Yahoo!7 (http://au.news.yahoo.com/sa/latest/a/-/newshome/14108165/lucky-escape-after-window-falls-from-plane/)

http://l.yimg.com/ao/2012/news/july/plane-windowjul2_630.jpg

[Lookleft]

How do you catch a flight from Tasmania to NZ?

[Bevan666]

I would say they were going to fly themselves. Hobart to Queenstown is 950nm.

Glad the window didn't pop 1/2 way across that leg!

[VH-XXX]

If they were going to the snow they would have been fine if they could reach their snow jackets.

[Captain Garmin]

Pilot and pax appear very relaxed given they could have been lunch for a great white.

What's your confidence level in pressurized kit-build aircraft now?

[dogcharlietree]

According to the Lancair website, this aircraft is pressurised to ONLY 5 psi at FL250.
Their TUC (time of useful consciousness) is 3-6 minutes.
They would have had time to have a cuppa before doing anything drastic. Sure it might have been a bit chilly, but really.
Think about the guys up around 50k that have a PSID of around 9 and TUC is around 5-8 SECONDS (not minutes).

[Old Akro]

Only 5psi at FL250? That's probably an 8,000ft cabin altitude or less. I think that is as good or better than any other pressurised light aircraft. Work out the force over the entire area of a part (say door) at 5psi. Its pretty significant and requires pretty good engineering.

I'd suggest that the only people that think dealing with this is easy haven't done hypoxia training and / or had a window / door issue in flight.

[dogcharlietree]

With all due respect Old Akro, you have probably heard of the old saying "there I was, 50,000ft, nothing on the clock but the makers name and that was in French......" Well, my mate, I've been there in THAT EXACT situation and it happened to me. (Gliding properties of a brick...ring a bell?). So I would say to have it at 25,000ft would be a walk in the park compared.

[OZBUSDRIVER]

Just a heads up. The owners are pruners and are OK. :ok:

[FokkerInYour12]

Better photo here:
http://mail.lancair.net:81/lists/lml/Message/62216-02-B/photo.JPG
(http://mail.lancair.net:81/lists/lml/Message/62216-02-B/photo.JPG)

[havick]

Just out of curiosity, is a structural failure like that an insurable event or does the owner shell out for cost of repairs?

[Howard Hughes]

Was that you baswell?;)

[baswell]

Just taking the "how dangerous is this" trend to its logical conclusion. ;)

[ForkTailedDrKiller]

That WOULD get your attention!

Dr :8

[VH-XXX]

It's hard to tell what actually fell off. It lost the door and. It just the window, however it took a lot of airframe too. It's like the door catches pulled part of the airframe off.

[OZBUSDRIVER]

I think the IV-P has only one door.

[Arnold E]

I think the IV-P has only one door.

Yep.................

[Jabawocky]

Folks

The lancair involved had a WINDOW blow out NOT a door. They have one door, unless otherwise informed, I take it that it is very similar to the IV next to me with a LH door only.

[VH-XXX]

Yep, that makes sense, one door.

It certainly took a lot of airframe with it, that's for sure! Note the rear half of the airframe piece that is missing.

Looks like the window goes right from the bottom to all the way up top but is painted to look smaller and there is some internals where the arm rest is. The window was well and truly attached in some areas so it was seemingly a massive force that tore it off.

[nitpicker330]

Wow, that will be hard to fix and still allow the cabin to be pressurized.

[jas24zzk]

Nothing a bit of bondo and some cling wrap won't fix.

[donpizmeov]

Hundred mile an hour tape will fix it. Well done to the pilot for getting it down safely. A very rude way to be woken in the cruise.

The Don

[Shagpile]

Very sexy aircraft - I want one! Are they severely limited to bitumen strips given the landing speeds?

[jas24zzk]

some very long unsealed strips out there

[baswell]

And if the pilot got knocked out in such an incident, the passenger just hits the big red button:

Seeker (http://www.x-plane.com/hardware/evo/9_seeker/Seeker.html)

[BEACH KING]

And if the pilot got knocked out in such an incident, the passenger just hits the big red button:

Seeker
:ooh: Wow, the future of GA is coming along nicely!

[Typhoon650]

Given the construction of the Lancair, that's very disturbing. I also think the airframe is a write off.

[VH-XXX]

To be honest, it would be easily repaired for a fibreglass / carbon guy. Looks like the flock let go that was holding the window on. They may not actually be screwed in but rather just glassed in so once the wind god under it, the airflow peeled her off.

If they were the builder of the aircraft they could fix it themselves or at a low cost.

[Jabawocky]

The window is screwed in, bonded and glassed.

If you could find the window it would be interesting to see.

The clean radius corner (front lower) is a sign of possible failure, the rest just got torn away.

The screw holes are larger than the screw and the edge gap is to prevent stress risers I am told. So perhaps something started in that corner.

Will not be an easy repair in any case. Not as a P model anyway. I would want a very smart composite engineer working on the repair, and prepared to sign/fly it himself.

[VH-XXX]

If there are screws then, that is an amazing amount of damage to tear them all out!

You'd think that even if a corner of the window was exposed to the airflow it wouldn't even rip off if it was all screwed in.

I guess that's what happens when you go so fast!

There are some interesting pics here of one being put together.
AirCrafters Lancair IV-P Turbine Construction (http://www.aircraftersllc.com/projects/rsl4p/index.htm)

[Ovation]

This incident prompted me to try and understand the forces that are acting on the window.

If the differential pressure is 5 psi and the window is (guessing) 24" x 24", then the area is 576 sq inches and the total force is 2,880 lbs/1.28 tons/1.31 tonnes.

The assumed circumference would be 96" and if the pressure is evenly distributed around the edge, then the force at the window/fuselage connection would be 30 lb per inch.

The window separated over water just west of Kangaroo Island (according to the FlightAware track log). It is unlikely to ever be found unless netted by a fishing trawler.

[Typhoon650]

VH-XXX said:
To be honest, it would be easily repaired for a fibreglass / carbon guy. Looks like the flock let go that was holding the window on. They may not actually be screwed in but rather just glassed in so once the wind god under it, the airflow peeled her off.

If they were the builder of the aircraft they could fix it themselves or at a low cost.

This isn't a quick bog and fibreglass repair kit from Bunnings job. That would be like bogging up the sills of a rusty car, looks pretty but no structural gain.
The photos show a structural failure and delamination of the laminate over a significant area, in a very important part of the structure.
If the aircraft was made using pre preg, vacuum bagging or similar, I personally would be very worried about the rest of the structure (how it's construction is, any damage). Any pressurisation induced structural failure of an aircraft is a very serious thing.
I have 20+ years of working with composites and using structures made of them, I think I know a decent failure when I see one.

[Wally Mk2]

I'd think the owner would also be thinking that his airframe now has a 'stigma' attached to it for any future selling of same. Bit like damage history to any airframe,no damage is a big ticket item when selling an airframe.

Who would by a second hand home built pressurized plane now that it has had a structural failure?Could be interesting times ahead for the owner.
At least they are safe after an amazing event:ok:

Wmk2

[jas24zzk]

Probably be cheaper to simply build a new fuselage and use everything else from the damaged a/c.

Be interesting to see if they'd permit you to do it that way. New fuse + serial number, using old wings etc.

hmm

would bring new meaning to a fast build kit i guess. :E

[VH-XXX]

Trust me, it's repairable. If they wrote off the fuse, send it my way.

You'd be amazed what can be done with fiberglass. I've seen aircraft smashed in many parts with cracks right through them repaired and flying again with moderate ease.

What looks like major work to a pilot, to a fiberglass guy may be a walk in the park. I once knew a guy that was an absolute whizz with glass, everything in his house was made from it. Plant pots, steps, spa bath, pool, boat, car, bike!, kitchen cupboards; he made it all himself, first with moulds from timber and away he went. Disappointingly he left the industry and started selling Telescopes of all things. If that was mine I'd send it his way and I'd have it back a week later as good as new. Less guys do carbon fibre which is a shame.

[nitpicker330]

Well I guess they could fly it without pressurization in the future, it wouldn't need to be beefed up then. Wouldn't be too hard to patch up for non-pressurized flight.

It could still fly around at FL180 with Nose tube Oxy at very fast speeds.:ok:

Not a total loss then.

[baron_beeza]

Did someone say the owners frequent the forum here.

I doubt this aircraft is conventional fibreglass, the thought of that kind of pressure differential concerns me. I don't have a composite rating but I do drive a fibreglass car. Repairs to the car are easy enough, much as the repairs on typical GA aircraft. Just the Epoxy and Polyester thing to work out.
Perhaps I am mistaken but I was thinking the aircraft may have been constructed out of a more advanced composite.

This aircraft has suffered damage, possibly both the obvious and some that is not. This may have been a fatigue issue as opposed to an overstress or localised failure.

It may well be that the fuselage requires testing to determine what caused this failure. I am sure it won't have gone unnoticed by the manufacturers or the regulators.

There may not even be a repair scheme for such damage also. I am not at all familiar with the type. The factory may want to have a good look at it. Is there a possibility other similar aircraft may be affected for example ?
The guys were certainly very fortunate to get out of that one with both their lives and much of the aircraft. It is much like the Aloha 737 in many respects.

[PLovett]

The aircraft is not conventional fiberglass. Lifted from the Lancair web site....


Materials
We utilize advanced composites for one single reason; they are clearly the best overall airframe materials for a general aviation aircraft. These materials permit complex aerodynamic shapes that would be impossible in aluminum and they can maintain exact airfoil contours and surface finishes that provide the high levels of laminar flow available on our advanced airfoils. These composites also do not rot, rust or corrode. They can be tailored, ply-by-ply, to perfect the load bearing structure. Opposite of aluminum, composites have a near infinite fatigue life and the carbon fiber we use is, pound for pound, nearly three times stronger than steel.

With the Lancair IV and IV-P requirements for reduced weight and extreme high speeds, a small, strong and stiff wing was essential. Carbon fiber was chosen because of its incredible strength to weight ratio, which is generally 25% lighter than E-glass as well as 2 times stiffer. These materials are becoming very common for general aviation aircraft today.

Sandwich Structures
Typical ply schedules for the airframe will range from three to as many as seventy plies of carbon fiber, depending on the load requirements. These carbon fibers are typically woven materials; however, spar caps, longerons, and roll over structures are fabricated with uni-directional carbon.

To complete the sandwich structure, only Nomex honeycomb core materials are used. These premium materials are again the aviation industry standard due to their high strength in both compression and shear along with their fire resistant characteristics.

The resultant structure is comprised of several layers of woven carbon fiber, a film adhesive layer on each side of the Nomex core, and followed by closeout layers of woven carbon fiber. This creates an amazingly stiff, strong, and light composite that is capable of outlasting any aluminum structure. And again unlike aluminum, composites are far more damage tolerant and virtually cannot be permanently bent.

Incidentally, a 5.0 psi pressurisation differential.

[VH-XXX]

To sum it up.... they use Carbon Fibre to build it.

From the websites I've seen, the fuselage comes as a kit with the windows not fitted. This means room for user error despite best-efforts at the factory.

[T28D]

Looks like it needs a lay up schedule from High Modulus to me,the little patch torn away behind the windowthat is regular in shape is quite revealing

[VH-XXX]

Re: Fatigue, the aircraft is 12 years old. Hard to know how much work she has done being a private aircraft.

[blakmax]

Those who follow PPRuNe would be familiar with my comments on composite and adhesive bonded structures, especially rotary wing failures.

I would need to see close up photos to make any definitive abservations, but just from a cursory examination of the available photos;
1. There appears to be a region of bare metal(?) at the forward top of the failure. If that is metal and if it is bare, then that is a surface preparation issue.
2. There are areas on the bottom rail where the adhesive appears to have disbonded from that frame.
3. There are areas over the core where there appears to be no adhesive, which suggests a bonding issue between the core and the adhesive.
4. There are areas over the core where there is residual adhesive which appears to have separated from the skin.
I note that the manufacturer is proud of the use of Nomex core and high strength composites. While if correctly used and handled, these materials can perform well ion structures, their selection for home made kits is of concern. Composites, adhesives and nomex all absorb moisture from the atmosphere both prior to manufacture and after manufacture and that moisture can have deleterious effects. Critically, the moisture absorbed during manufacture can have consequences with regard to the integrity of adhesive bonds such as between the skin-to-adhesive bonds and core-to-adhesive bonds. Now I have measured up to 5% water absorption levels for nomex core and composite resins and adhesives may absorb 1-2% moisture prior to cure. That moisture may inhibit chemical reactions at bond interfaces, and may also lead to hydration effects at interfaces in later service.
The way to prevent moisture issues is to perform bonding and composite processes only in an environment where the humidity is low. The requirements are buried in an FAA Advisory Circular AC 21-26 para 8 a (2) a. Now I doubt that any back yard kit builder can meet those requirements.

Better phots would help.

Regards

Blakmax

[blakmax]

I am a specialist in adhesive bond failure forensics. If the owners want to PM me, I will see if I can help identify the cause of the failure. The cause may be of interest to other owner builders.

Regards

Blakmax