Woodcomp prop throws a blade.

[wags]

On Sunday 31st August a Czech Airworks "Sportcruiser" was conducting circuits at Gympie Airfield with the aircraft's new owner and an instructor onboard. Slight vibration was felt throughout the aircraft during initial climbout and x-wind legs of a circuit. The instructor reduced power somewhat but approx 30 secs later a very loud "explosion" occurred and the engine came to an abrupt stop. A short stub of one blade of the 2 blade Woodcomp inflight adjustable propeller was visible protruding over the cowling. The aircraft subsequently carried out an emergency landing back onto the airfield without further incident. The occupants suffered no injury other than to their nerves.

 

The aircraft was virtually new (50 hrs or less?) and had not exhibited any previous propeller problems that I am aware of. What remains of the prop stub displays what looks like water seepage (or similar) has occurred between the wood laminations of the blade, but this fact will need to be confirmed by investigators.

 

The engine has obviously "twisted" on its mounts with at least two mounts showing indications of significant distortion. The engine exhaust stub had moved approx 100 mm or more and impacted the nose wheel mount with sufficient force to dent the exhaust pipe itself. Both carbies of the Rotax 912 had disconnected themselves from the intake manifold and no doubt aided in stopping the engine before further damage occurred. The strength of the airframe no doubt contributed to a safe outcome for the occupants of the aircraft.

 

The outcome of an investigation into this incident will be interesting to read as this would appear to be a catastrophic failure of what could be considered as a brand new propeller. It will almost certainly require replacement of everything from and including the firewall forward.

 

I for one will take more than a precursory look at the blades of my prop during any preflight from now on looking for signs of any tell-tale hairline cracks or indications of delamination starting to occur, especially around the hub area.

 

 

[Guest brentc]

One of those recently came to grief in the US too. The first fatality. They were lucky!

 

Date: July 21, 2008 Newark, IL

 

Aircraft Type: Czech Aircraft Works Sport Cruiser, N602CF

 

Narrative: A/c sustained substantial damage when impacted terrain near Cushing

 

Field (0C8). A/c was registered as Special - Light Sport Aircraft (S-LSA), and

 

operated as rental by Sport Pilot Chicago, located at 0C8.

 

Death/Injury: One fatality

 

Remarks: There were no witnesses to accident. Visual meteorological conditions

 

prevailed at time of accident, and no flight plan filed.

 

Date: July 21, 2008 Newark, IL

 

Aircraft Type: Czech Aircraft Works Sport Cruiser, N602CF

 

Narrative: A/c sustained substantial damage when impacted terrain near Cushing

 

Field (0C8). A/c was registered as Special - Light Sport Aircraft (S-LSA), and

 

operated as rental by Sport Pilot Chicago, located at 0C8.

 

Death/Injury: One fatality

 

Remarks: There were no witnesses to accident. Visual meteorological conditions

 

prevailed at time of accident, and no flight plan filed.

 

Date: July 21, 2008 Newark, IL

 

Aircraft Type: Czech Aircraft Works Sport Cruiser, N602CF

 

Narrative: A/c sustained substantial damage when impacted terrain near Cushing

 

Field (0C8). A/c was registered as Special - Light Sport Aircraft (S-LSA), and

 

operated as rental by Sport Pilot Chicago, located at 0C8.

 

Death/Injury: One fatality

 

Remarks: There were no witnesses to accident. Visual meteorological conditions

 

prevailed at time of accident, and no flight plan filed.

 

Date: July 21, 2008 Newark, IL

 

Aircraft Type: Czech Aircraft Works Sport Cruiser, N602CF

 

Narrative: A/c sustained substantial damage when impacted terrain near Cushing

 

Field (0C8). A/c was registered as Special - Light Sport Aircraft (S-LSA), and

 

operated as rental by Sport Pilot Chicago, located at 0C8.

 

Death/Injury: One fatality

 

Remarks: There were no witnesses to accident. Visual meteorological conditions

 

prevailed at time of accident, and no flight plan filed.

 

 

[wags]

Brentc please do not think I am saying that the Sportcruiser itself had a problem.

 

In fact quite the opposite.

 

Any lesser constructed aircraft might well have ended up loosing its engine and that would have spealt disaster for the occupants with a sudden shifting aft, and definitely out of limits, of the CofG. The fact that engine mounts were broken and the engine "twisted" so much without becoming detached from the airframe is a testament to the strong construction and quality of build of the Sportcruiser.

 

The fact is that a "new" propeller failed for whatever reason - but the investigators will determine that fact.

 

Perhaps this incident suggests we should all practice our emergency landings on a regular basis.

 

Wags.

 

 

[Guest Andys@coffs]

Brett did it crash 4 times or did you have the DT's when using Ctrl V:big_grin:

 

Andy

 

 

[facthunter]

Engine mount strength.

 

When a prop sheds a blade, generally the engine will come out. I recollect a chipmunk doing that near Lake Macquarie and the aeroplane being so tail heavy after the engine fell out, it spun in to the lake. I believe the pilot was not injured, as without the mass of the motor,in the spin, the A/C had a lesser rate of descent, compared to normal. After that the spinners were left off those aircraft to conduct more frequent inspections of the hub section of the Fairey-Reid props. (which were metal fixed pitch).

 

An Ansett DC6b lost part (or all) of a prop blade near Essendon and the engine (RH Inboard, I believe) was just hanging by a few pipes. As the crew decided that the engine might fully detach during the landing and have the main gear run over it. and cause major problems, the aircraft went over Port Phillip Bay and the engine was shaken loose . Dramatic stuff Eh! Just another day at the office. Couple of cleansing ales afterwards. Long time since I have said that... Nev.

 

 

[Mick]

Interestingly during our recent visit to the USA there were a couple of people in different locations and with different aircraft mention that they have had problems with Woodcomp blades de-laminating. One of these people had had it happen a couple of times, the second with a (new) replacement blade. Of course being in the USA and under LSA regs these were ground adjustable props.

 

I personally used a Woodcomp ground adjustable prop on our Sportstar for 210 hours with no problems.

 

 

[Guest brentc]

It crashed 4 times in total. It took one hell of a beating and cost the owner a fortune in repair bills

 

 

[Guest Maj Millard]

Props...the highest stressed component on the whole aircraft (except maybe the pilot), #2 is the crankshaft. A prop with any weakness is a danger to us all, I don't care who makes it, and it should be withdrawn from use, in my opionion.

 

Shades of that classic, the wood blade GSC. Had one of those throw a blade up here once, it completely destroyed the other two blades, with only the hub remaining on landing. Similar damage by the sound of it, severe engine mount twisting, engine mount bolts (an6s) heads pulled clean through thick washers leaving a perfect print of the bolthead. All mount bolts bent. And the one loud bang throwing off both carbs , to instantly stop the engine, which is not a bad idea.

 

Had a friend years ago throw a blade on an early 2 stroke, no problem he rapidly thought, I'll turn off both mag switches......engine shaking so much wires had broken, so that didn't work. Then he turned off the fuel (you do have a fuel shut off don't you ? ) He said that the 30 seconds or so that it took for the damn engine to run out of fuel, were the longest 30 seconds of his life, as he hung on waiting for the engine to depart.

 

Recently spotted a 912 engine factory installation (Tecnam I think, but don't quote me ) where there were steel brackets running from the intake manifold to the carbs, to stop them from falling off. Watch out in those, if you loose a prop blade anytime.

 

On the previous mentioned blade failure ( 912 Lightwing ) the engine mount is very substantily built. The same engine, (read:energy potential) in an SS4 Storch, sits in a much weaker engine mount that possibly could fail under similiar circumstances. Strange thing is, both mounts were designed by the same CASA approved CAR 35 engineer, and both are in CASA certified factory built aircraft. Onya CASA. Go figure..........

 

As a footnote: the formula one racers at Reno who run really wild engines and props, to achieve as much performance as they can, often have safety back-up cables taped to thier engine-mounts. Have they learnt from experience ?.

 

 

[Guest Maj Millard]

Hey Brentc, I've had the odd one -time crash, but never a four- time crash, that was really exciting....not.

 

 

[johnm]

photos

 

I think there will be 2 photo's attached to this email

 

One shows the broken blade

 

One shows carbbies pulled from engine - by forces when blade broke

 

This is not a reflection or comment about the 'aircraft and hardware' used in this thread - it just shows you what could happen up front

 

 

 

 

[Guest Michael Coates]

Note Michael Coates has been banned from this site

 

 

 

 

 

 

 

[Guest ozzie]

I won't mention that crappy looking plumbingthumb_down

 

 

[johnm]

There was no plumbing installed in the aircraft - this option not installed (and I doubt whether available)

 

I am told however, if there was such plumbing installed - it would of been put to great use

 

 

[Guest becky1]

Hi everyone,

 

Just to set the record straight I was flying the aircraft when the propeller snapped on early downwind.In reference to Michael Coates comment about there being another lesson to be learned here by not pulling the aircraft around by the prop,this definately was not the case in this particular incident and perhaps if Michael had all the facts which are well known now to the investigating authorities,he may not of insinuated that this may have been a reason for the failure especially when the aircrew involved can read it on this forum

 

The pieces of the propeller have all been found and proven to be faulty. The aircraft and prop had done a total of 96 hours and had been moved around the hanger with a towbar with extreme care,the aeroplane has never spent a night outside,it was always thoroughly preflighted and the lack of glue on the wooden section inside the carbon outer sheaths could not be seen,so no one had any idea there was about to be a failure.

 

It was a frightening experience especially when it happened with no warning and such a violent bang and a jarring right through the whole aircraft. both my student who also owns the aircraft and I were very fortunate that the carbys did come off the engine which stopped it straight away as I doubt our reaction time could never have been quick enough to turn it off before further damage to the engine mounts and firewall which may have resulted into something far worse than a deadstick landing

 

Jennifer

 

 

[Brett]

I thought Michael's post was informative for me and didn't think he was insinuating anything,, I have seen people b4 at times pulling aircraft around by props and never thought anything of it ,,I'm glad he mentioned it as for one I have learned something..

 

 

[BLA82]

I thought Michael's post was informative for me and didn't think he was insinuating anything,, I have seen people b4 at times pulling aircraft around by props and never thought anything of it ,,I'm glad he mentioned it as for one I have learned something..

I couldn't agree more Brett, I have seen it alot aswell and I thought it was common practise now I know different. I don't think there was anything insulting about Michael's post.

 

 

[Guest basscheffers]

Jennifer, I also agree it doesn't sound like insinuating. I find it useful for someone with experience to point to all the things that could lead to an incident such as this, not just the exact cause of this specific incident.

 

I've never pulled a plane out by the prop, but never thought of why this would be a bad idea before now. That's useful information!

 

 

[BigPete]

Hang on a minute - I've always pulled my Jabiru out using the prop. Two hands, each one right next to the spinner as close as you can. This what I was taught to do. I mean, the propellor pulls the whole 'plane through the air. What have I missed?

 

regards

 

 

[turboplanner]

BigPete, so was I in GA - both hands against the hub AFTER checking mags.

 

However I know of a few Jab props showing small cracking near the trailing edge towards the tips where the most obvious cause would be bending to a lesser pitch by size 10 hands.

 

 

[wags]

Handling of props and blade failure.

 

I read with great interest the suggestion that pulling an aircraft around by the prop can lead to blade failure, delamination etc. I must have missed something in 40+yrs of aviation and nearly 20,000 hrs flying because I was taught right from the beginning to grab the prop with a hand close in either side of the hub to move aircraft if a tow-bar was not available. No aviator in their right mind would put a load such as this on a prop at any point other than close to the hub. Moving an aircraft in this manner, done correctly, would not subject the prop to anything more than a fraction of the loads imposed on it during normal operation.

 

The facts associated with this particular failure are that the propeller involved in the incident (which could have been castastrophic for the occupants of the aircraft) was virtually new and the prop failed from the inside out. Inspection has revealed a lack of glue on the laminations of the blade core which is made of wood. The covering sheath of carbon fibre was shed as a whole piece from both the front and back of the blade indicating there was movement within the core under the covering sheath. One can only draw the conclusion that it appears this prop failed due to a possible lack of quality control by the manufacturer or similar. The fact that there are other cases of the same brand/type failing because of core delamination around the same time confirms there might be a problem with the manufacture of that particular brand/type of prop. This prop was eventually going to fail regardless of how it was handled.

 

What I find very disturbing about this incident is not how we should or should not move our aircraft around a hangar, it is the failure of authorities to prohibit further flight by aircraft fitted with the same brand/type of prop until they have been fully inspected. Not just a visual inspection looking for cracks and signs of wear as directed in the AD, but a full and thorough inspection possibly even involving x-raying (or similar) of all blades. If I was flying an aircraft with this brand/type of prop I would be doing a whole lot more than simply looking at the prop before I flew the aircraft again!

 

You can be sure of one thing - in a large majority of aircraft types we fly under the RAAus banner, if the motor comes out in flight the aircraft will more than likely be uncontrollable with a disastrous outcome for the occupants. The crew involved in this incident were extremely lucky in the circumstances.

 

 

[Guest Johnmac]

Where have you all been, the accepted and correct way to move an aircraft is to pull via the prop as close as possible to the spinner. It is not, and never has been acceptable, to pull an aircraft by the tip of the prop, even so as I understand it the prop delaminated and expert examination has shown failure of the "glue", end of story.