Flying after bumping the wing during taxi

[John R81]

I am a heli pilot so know nothing of aeroplane flight / safety.

At Redhill yesterday I witnessed a small GA aircraft taxi along and its right wing hit a parked van. The van must have been a couple of inches taller than the clearance under the wing. The machine tipped up visibly to go over the roof, and then dropped sharply as it finally cleared the rear. So one part of the wing ran along the corner of the roof of the van. I expected the pilot to stop (I thought he must have noticed that!) but he made to line up 18.

My friend called the tower to tell them of the impact and warn the chap, and subsequently he reversed course and pulled up. Then he exited the machine and inspected his wing. He walked back to the van, and took a good look at the floor around about (he did not seem to pay much attention to the van itself). Then he got back into his machine, fired up and lined up 18 for departure.

I went down to the white van, which had red paint from the wing scraped along the roof edge; so the impact was enough for that at least.

Now, being a helicopter pilot whose machine performs public transport work I would have needed an engineer to sign-off that my machine was safe to fly if I bumped anything at all.

Was this pilot's actions really all that is needed to go flying in a non-public transport aircraft?

[Gertrude the Wombat]

Fatal accident not that long ago after a wing-tip collided with a straw bale at the side of the runway - the wing then collapsed in flight.

[mad_jock]

Write that up as a MOR if he just flew off.

Silly sod.

[Genghis the Engineer]

'wot Jock said.

The leading edge of an aeroplane wing is both structurally and aerodynamically utterly critical to safety. As reported, this idiot was endangering his life and that of anybody in or under the aeroplane. It needs reporting PDQ in case anybody else tries to fly it before this is inspected and if required, rectified.

Report it, quickly.

G

[mad_jock]

AAIB might be a good shout as well. The MOR's are about 3 months before anyone looks at them last time I heard. Or whistle blowers might work.

how the hell does an aircraft get within striking distance of a van anyway?

[JUST-local]

GTW, do you have a link or any other info on the a/c that crashed following hay damage, I have heard about it before but cannot find any other details on it.
Thanks.

[John R81]

I have to admit I was stunned that anyone would take-off after that. I was not sure if that was more a "helicopter" thing, or more a fact of my machines flying public transport so subject to tighter rules.

I was also suprised that he thought it was OK not to find the van owner and let him know he had hit it - though the red paint will likely T-Cut out.

As posted, the event was reported to ATC at Redhill. That is a full, qualified ATC service and I would hope that ATC is required to report any collision happening on their watch. My understanding is that the Pilot is required to file a report with CAA (Mandetory Occurance Report?). So that's 2x reports. If you think it would be helpful for me to also report, to whom do you suggest?

[madlandrover]

If the wingtip took an impact force, think of the moment arm and the effect on the wing root...

[mad_jock]

Air Accidents Investigation: Contact Us (http://www.aaib.gov.uk/contact_us/index.cfm)

Try phoning them and ask them who you should contact.

It more for the poor sod that flys it next than anything else.

By rights if there is an airside prang and ATC know about it they have to get the police in. Its actually quite serious.

['India-Mike]

JUST-local

Think this is it..

http://www.aaib.gov.uk/cms_resources.cfm?file=/dft_avsafety_pdf_500558.pdf

If another is being referred to though I'd like to read about it too.

[Pace]

If it was true that the aircraft was not his then it sounds likely that he hoped no one would notice especially the owner and he could walk away as if nothing had happened.
The aircraft should be inspected for anything but the slightest touch as you cannot see what damage may have been done.
It would not be nice for the owner or someone else to find out later that there had been damage at their peril.

I hope someone gave a note to the owner telling him what occurred

Pace

[maxred]

Well you could call the CAA, Monday morning, file a CHIRP, get ATC to lodge an MOR, I assume everyone has the reg detail??

Few years ago a clown took out the fence on departing Glenforsa, and was last seen heading to Edinburgh with barbed wire, and a large post trailing behind the aeroplane:( A PA28. Pilot well known.:\

So the story goes, the next morning, takes the blue and white tape off said aircraft, and flew it to another airfield for repairs. Totally astonishing.

He kept his licence. It truly amazes me that there are still individuals who put their own life, and others at risk by doing things that seem extraordinary when you witness it.

Nah, report him asap

[John R81]

MJ - I emailed AAIB from the site link. Reg included.

Aircraft was a Rans-S6E SD. so you will appreciate that a Peugeot pannel van is not going to fit under the wing!

John

[mad_jock]

I would give them a ring as well and just ask. Its more to make sure some poor sod doesn't take the aircraft up to do stalling or steep turns tomorrow morning before everyone gets there poo together and starts clearing out the mail boxes.

They might not be interested and want you to call someone at the CAA.

I would definatley call then after you have put the type in.

If it was a C172 I wouldn't be that worried, they are built like brick poo houses and I have flown one after an engineering inspection with 2/3 of the leading edge battered by a bird strike. But at least its only a single seater so no one will be training tomorrow in it.

[Cows getting bigger]

The fact he bashed his wing in the first place says enough. Muppet. Doesn't deserve to share the sky with the majority of us.

[patowalker]

But at least its only a single seater so no one will be training tomorrow in it.

The Rans S6 ESD is a two-seater, but there will be nobody training in it tomorrow, because it is a homebuilt.

Yes, I know, the owner(s) can receive training in it, but then he probably believes he has received all the training he needs :)

[bingofuel]

Is the Rans not a permit aircraft, and as such maintenance can be done by the owner, and an inspector does the permit renewal?

I am not for one moment saying what the pilot did was good practice, but under the permit scheme can the owner not sign off his own repairs etc.?

I am just curious if legally as pilot/owner he can claim he examined the aircraft for damage, and is authorised to deem it fit to fly with no further duplicate inspection?

Any PFA/LAA inspectors On here able to tell me the procedure?

[ATCO Fred]

The Aviation side aside - having caused damage to a parked vehicle and then leaving without leaving his details has he not committed a criminal offence??

[BEagle]

Some years ago, a couple of my instructors went over to the maintenance aerodrome, so that one could pick up an aircraft after a 50 hr service....

Despite being warned by his colleague, the PIC hit a fence post with the wing tip whilst trying to turn round. His colleague suggested that they should leave the aircraft at the maintenance aerodrome and fly the other one back. But no, the PIC decided to fly back to our home aerodrome, whereupon he told me "I've had a bit of a bump"...

I went to look at the aircraft and immediately grounded it. Then we had to arrange for the maintenance people to drive over and check that it was OK to fly it, so I could fly it over to the maintenance aerodrome to have it repaired.

It was pronounced safe, so I flew it over and did a low speed handling check on the way - to find a slight wing drop at the stall. Handy to know that as the maintenance aerodrome had rather a short RW. I then waited whilst they repaired it, but we decided to leave the repair in primer until the next 50 hr was due.

A completely avoidable taxying incident. But even worse was the fact that the FI couldn't accept that his decision to fly it back was unsound. Plus it cost us 2 x road journeys for the maintainers, 2 x transit flights to take it over for repair - and I had to hang around for a few hours so wasted my own time.

We docked the price of the repairs and the maintainers' road mileage from the FIs pay, but waived the 2 transit flight costs. Had he just left it at the maintenance aerodrome in the first place, I'd have been more lenient. But his stupid decision and pig-headed reluctance to learn from the error of his ways didn't impress me. I was very close to advising him that we no longer required his services.... But I was conscious of the fact that he had no other regular source of income.

I also made him read that Robin / haybale accident to which reference was made earlier.

Before it may be flown, an aircraft must be checked by licensed maintenance personnel following even the slightest ground collision.

[John R81]

Fred - No, I don't think so.

On a UK road then it is an offence for a person being the driver of a mechanically propelled vehicle and owing to the presence of that vehicle on the road or other such public place an accident having occurred whereby damage or injury was caused did fail to stop and give his name and address and identification marks of the vehicle.

Road Traffic Act 1988 s 170 (2)

If there are reasons for leaving without contacting the owner fo the vehicle then the accident should be reported to the Police within 24 hrs. Technically, there could still be a prosecution but if it is a non-injury accident it is not typical for that to happen.

However, this was on an airfield which has a gate and controlled access. Hence I don't think it qualifies as part of the public road (which would be the case in, say, the car park of Burger King).

John

[Genghis the Engineer]

Is the Rans not a permit aircraft, and as such maintenance can be done by the owner, and an inspector does the permit renewal?

I am not for one moment saying what the pilot did was good practice, but under the permit scheme can the owner not sign off his own repairs etc.?

I am just curious if legally as pilot/owner he can claim he examined the aircraft for damage, and is authorised to deem it fit to fly with no further duplicate inspection?

Any PFA/LAA inspectors On here able to tell me the procedure?

I'm a BMAA inspector, but an LAA member.

No, he isn't allowed to sign off his own repairs, EXCEPT where it's through replacement with "identical" parts solely, and then it should normally be counter-signed by another PPL, or by an LAA inspector.

In a case like this, if there is any damage not simply fixeable before next flight by replacement of parts, he should inform LAA engineering, they are likely to suspend the permit. The LAA will then get a report on the damage, agree with the owner (or just impose) a repair scheme, which once done needs signing off by an LAA inspector (who may not have done the repair work themselves). Not unlikely that a check flight would also be required.

For major repairs, he'd also (probably) need a letter of "no technical objection" from the designer.

G

[mad_jock]

I have a sneaky feeling that if there is a prang airside between an aircraft and any form of motor you have to inform the British Transport police.

[bingofuel]

Thanks for that Genghis! I suppose it doesn't really matter if permit or CofA, if the guy flying does not have the sense to get something checked, no rules will stop him taking off.

[frontlefthamster]

From their website:

British Transport Police is the national police force for the railways providing a policing service to rail operators, their staff and passengers throughout England, Scotland and Wales.


Two things must ye know about the Mad Jock...

The offence here may be endangerment but the pilot will, of course, get away with it.

Can the OP remember anything about the registration?

[bingofuel]

MJ. I think the BTP only have authority where railway trains are involved or on railway property. Not sure if or when they had any juristiction over aircraft.

Edited: beaten to it by Capt Hamster

[peterh337]

Where I am based, one renter started up with the towbar attached. He took ~ 1" x 1" piece out of the prop, chucked the mangled towbar into some grass, went for a flight, landed, said nothing. I saw the dent myself. The school never got anything from him, so it was an insurance job.

Sounds completely reasonable. I mean, if you hit a stone with a lawn mower, and it runs OK afterwards, you just carry on, so why should a plane be any different? The engine looks and sounds pretty similar to a lawn mower, and is even harder to start.

I am saying this only ~50% tongue in cheek, because PPL training does not mention shock loading at all (IME) so if the "pilot" is merely trying to avoid getting into trouble, it's perhaps not all that suprising. One should judge people only by reference to their training.

[John R81]

FLH - post 13.

I also have photo if needed.

John

[BackPacker]

If the wingtip took an impact force, think of the moment arm and the effect on the wing root...

I don't have to imagine that. I have seen the damage that was done to the spar and spar box of a PA28 after a more or less similar taxi incident. The wingtip was dented but that was the easy fix. Fixing the spar box was a major structural repair job that lasted three months or so.

But that taxi incident was duly reported and the aircraft immediately grounded.

Wings are designed to take load mostly in the vertical. In the horizontal plane they're relatively weak. In fact, glider wings have a special diagonal spar in them to handle the horizontal loads that result from a winch launch.

[3 Point]

peter 337, Don't get me started on towbars!

My aeroplane had a towbar incident just like you describe (before I owned it). I am absolutely firm about this; You fit the towbar, move the aeroplane then remove the towbar and leave it on the ground beside the nosewheel. I am up to here with telling people not to leave the towbar on the noseleg :=:=:=

Instructors have a responsibility to demonstrate this sort of thing when moving aeroplane on the ground - it's all good airmanship!

Happy landings

3 point

[Torque Tonight]

Terrible airmanship and the straw bale accident immediately came to mind. He is not just endangering himself but also anyone who flies that aircraft in the future. If I was the van owner I'd be pretty irate as well.

My little aeroplane pulled its tiedowns out of the ground and ran free during a night of rain and gales on a landaway nightstop some time ago. I had a nasty feeling a wingtip might have hit the ground during its escapade before it was apprehended. I inspected the thing at great length but was not willing to fly it until I had an LAA inspector check the wing internals himself. To knowingly hit the wing and fly anyway is shocking. Perhaps the same mentality as the supermarket moms who grind down the side of adjacent cars trying to nose into parking slots and then hope nobody noticed.

[frontlefthamster]

John,

Post 13 doesn't help. G-INFO doesn't have a matching aircraft. Do you mean its reg ends in the letters SD?

There is no harm in posting an undoctored photograph here for all to see.

Frankly, this sort of event is just another disappointment in the catalogue of woeful behaviour from a minority of people who call themselves pilots but are incapable of exercising the judgement which that term assumes. Almost as bad as the authorities' (and their peers') unwillingness to tackle them.

Peterh, once again your post marks you out. Is common sense not a facet of the human condition in Brighton?

[Big Pistons Forever]

I once grounded a C 152 before an instructional flight. Even if my student has done a full preflight inspection, I always do a walk around the aircraft before getting in mostly looking for things hanging/dripping/loose.

This time something didn't look right on the horizontal stab. When I looked closer I realized there was a faint diagonal spanwise crease. When the engineer looked inside he found the spar was kinked:eek:. The damage greatly decreased the structural strenght of the tail.

Nobody fessed up but three flights earlier a dual spin lesson was flown (the spin is a required exercise for the Canadian CPL flight test). Knowing the instructor in question I am sure he grossly abused the aircraft with a over the redline pull out.

The bottom line is simple. If you think you have hurt the aircraft you must report it. Even small bumps can manifest themselves in major hidden damage which often will not be obvious on an external inspection.

[A and C]

While all above seem to want to hang draw and quater this guy I think it is time to play devils advocate.

What if the owner was an LAA inspector & licenced engineer who having inspected the aircraft has decided that the damage is a few scratches to the paint and a dented pride ? He will also have concluded that there is no structural damage to the aircraft and it is safe to fly.

The fact is that few of you above have the technical knowlage to asses the damage to this aircraft and none of you have actually inspected the aircraft.

On these pages the press is condemned for gross mis-reporting of aviation incidents and yet here we have the very people who cry fowl when the press mis- reporting jumping to conclusions with little or no hard evidence of the facts.

Trial by prune...........don't you just love it !

[Big Pistons Forever]

A and C

I suggest you re read the opening post.

So you are basically saying that the LAA standards for inspectors and licensed engineers allow for the kinds of people who need to be told by ATC to go and inspect their aircraft after hitting something while taxing:hmm:

I don't think I would be very impressed with that logic if I was a LAA licensed person......

[goldeneaglepilot]

If the impact was hard enough to remove the paint then I would hope if it was being piloted by an inspector or engineer then the inspection would be more than a simple glance at the wing, especially as at first the impact was ignored

[funfly]

A & C is pushing his advocation a bit methinks:sad:
With any aircraft it is not necessarily the pilot who ignores potential damage, it is the person who flies some time later, even maybe the next owner years later, who will have no indication of a fuse running....:=

[pudoc]

"For non-urgent requests" use email, from the AAIB.

I'd ring them if you don't hear from them soon, John. I feel for the next person who flies it, or for the persons house that plane next flies over.

Let us know how you get on.

[L'aviateur]

Lets be honest, any good pilot would have swayed on the side of caution and returned the aircraft to stand for a proper inspection. I know I would have, but then I value my life and don't take unnecessary risks.

[flybymike]

Just to pick up on A&C's devil's advocate point. As I understand it from the OP, the aircraft wing rode over the roof of the van and did not for example strike the van head on and spin around or anything like that. Under these circumstances most of the loading will have been in the vertical plane not the horizontal.

[goldeneaglepilot]

the aircraft wing rode over the roof of the van and did not for example strike the van head on and spin around or anything like that. Under these circumstances most of the loading will have been in the vertical plane not the horizontal.

That makes it OK??????????

had red paint from the wing scraped along the roof edge; so the impact was enough for that at least

How can anyone guess at the unseen damage? At the very least it needs properly inspecting. What a stunning display of airmanship (NOT) I hope red van man reads this thread - he can't be impressed either

[flybymike]

the aircraft wing rode over the roof of the van and did not for example strike the van head on and spin around or anything like that. Under these circumstances most of the loading will have been in the vertical plane not the horizontal.
That makes it OK??????????

I am merely being devilish...

[patowalker]

I went down to the white van, which had red paint from the wing scraped along the roof edge; so the impact was enough for that at least.

The Rans S6 ESD wing skins are dacron "socks" and colour is dyed into the fabric at manufacture, so the red paint could not have come off "the wing". The cosmetic (and non-structural) fiberglass wing-tips added to later models are painted, so this must be where the red paint came from.

The Rans can be flown safely with one of these wing-tips damaged or missing. I know because I have seen it done. Not in the UK, of course. :)

[Kengineer-130]

As a PPL & LAE, it is utter madness to take the chance after a collision like that! It is almost impossible to discover the state of the wing without a detailed inspection inside & out. :mad:.. The sad thing is as a lot of posters have already said, it will be the next poor sod who flies it or someone underneath the flight path who will pay the price.....

[A and C]

I am less interested in the technical aspects of this than the pprune court of justice that has condemned this guy with very little hard evidence and the statement of one eye witness who was questioning rather than accusing.

I have no evidence to offer one way or the other technically so I won't offer an opinion one way or the other, what I say is it is wrong to hang this guy without knowing the FULL facts.

Over twenty years ago now I was involved in recovering a PA38 that had been involved in a main landing gear failure while taxing, the flaps had been down when the gear failed and we recovered the aircraft without further damage to the aircraft. The next week I am having a cup of tea in the club house when on the next table I hear someone telling the assembled crowd that the flaps and wing of the aircraft were damaged beyond repair by the people who recovered the aircraft because they dragged the aircraft clear of the runway by towing it with the wing unsupported.

I may or may not think that the guy was unwise to fly this aircraft, but for me the issue is not a technical one, it is the way some of you are so keen to condem a guy with little other evidence apart from the comments of other posts that have offer little new detail of the original incident.

[englishal]

Does the Rans have a wooden wing spar? Wooden wing spars can hide damage very well, which was the case in the straw bale incident, and utter madness to fly without an inspection.

I know of a similar incident where one of two owners clipped something with the wing. He was going to repair it, but the other owner insisted it was inspected. Good job as there was a crack in the spar.

Metal spars are more likely to show the damage if they are damaged.

[goldeneaglepilot]

A and C.

I presume that you are qualified as an engineer and must have seen some things during your working life that have raised concerns when you have inspected them? My thoughts are that this thread is not about "trial by Ppruners" as you suggest but one of common sense. I am sure you will agree that damage following an aircraft hitting a ground based object can often be hidden within a structure and not immediately obvious to a quick visual inspection.

John who witnessed the incident is an experienced rotary pilot and in my opinion did the responsible thing by informing ATC, he has also acted as a true gentleman by not embarrassing the pilot further in public by publishing the photographs or registration of the aircraft.

The pilots actions in continuing his flight does raise questions of his attitude to flight safety, and it has rightly been said on here a failure due to hidden damage may not occur immediately so it could become an issue to someone flying the aircraft at a later date.

Perhaps if I reflect on my own experiences of issues with aircraft through damage that was not blatantly obvious, it will help explain why on a personal note I feel quite strongly about the pilots attitude to the damage. Some twenty plus years ago I shared a hanger with a well known aerobatic pilot, he had a very casual approach to fear - for his day job he was a deep sea saturation diver... His style of aerobatics was to say the least aggressive. One day he asked my opinion about the top wing of his Pitts special - at face value it looked fine. However when you tapped the top of the dbox construction near the center it sounded dead and pushing it with your fingers showed a surprising about of deflection. I suggested that needed checking by an engineer. He took my advice, he did not fly that day and when I saw him two weeks later he bought me a beer!! He explained that the engineers had discovered that the wing had failed, the glue had separated from the wood and the wing was close to a catastrophic failure - all not visible by quick inspection. Brian sadly died some years later when an aircraft he was flying in the middle east suffered structural failure in flight. The cause was thought to be due to previous unseen (and uninspected) over stressing of its construction that led to an in flight failure.

If someone in a car has a bump, its not too life critical. if it fails - you can pull over and walk. If you bump a boat and there is unseen damage below the waterline you have a chance if you can swim. However in an aeroplane its hard to pull over in flight and even harder to try to fly on your own (I have not seen anyone with feathers who can fly).

[A and C]

Firstly I did not criticize the person who started this post, all he did was report the incident and ask a few questions about fixed wing aircraft.

I think that by informing ATC and getting the pilot to stop and inspect the aircraft he acted in the correct way, by objection is to the uninformed posts that have been made by people who have not had a chance to look at the aircraft and have not the first idea of the scope of the damage.
Please remember that the pilot has had a chance to look at the damage and decide what he wants to do, I don't have the luxury of seeing the damage ( like most of the forum that have commented above) and so am not in a position to comment due to not having the data to do so.

I am deliberately playing devils advocate here simply because I see a growing tendency on these forums to jump to uninformed conclusions ( the worst are the drunk pilot threads!).

I would rather like to think that pilots would take a balanced view of things once all the facts were avalable but it would seem that in the days of 24 hour rolling news we are all expecting instant answers and so descending to the standard of the likes of The Daily Mail in what is written in these pages.

[patowalker]

Does the Rans have a wooden wing spar?

No, it is a aluminium tube, covered so tightly in dacron that an experienced owner would normally be able to see or feel dangerous damage by sighting and running his hand along it.

[thing]

( the worst are the drunk pilot threads!). Do you mean threads about drunk pilots or threads started by drunk pilots....:}

[flybymike]

Banning the latter would wipe out most of the late night contributions to this forum.

[thing]

As a mostly late night contributor to this forum I agree.

[flybymike]

That explains most of your posts then. ;)

[Pegasus912]

As an ex-Rans S6 owner who knows how solid that leading edge tube is, I'd be more worried about the mini-van! ;) However, the guy didn't do himself any favours by pretending nothing happened. I'm sure if he'd parked up immediately and given it a good look over, and perhaps left a note on the mini-van, this thread wouldn't be here. The S6 has the benefit that you can easily access all the important bits to check for any obvious damage, as patowalker alluded to above. I've not been to Redhill, do you often have mini-vans on the airfield?

[thing]

That explains most of your posts then. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif

I resemble that remark sir. Said he at ten past the midnight.....

[Dave Gittins]

At parts of Redhill (esp where I fly from, Hangar 8) road vehicles share the taxiway in front of the hangars. So, yes, vans do use the airfield .. so do bloody great wagons !

The road to the control tower and the taxiway are also one and the same.

Indeed one of the runways (07 - 25) is part of the old perimeter road - and only as wide.

Joining Procedures - Redhill Aerodrome (http://www.redhillaerodrome.com/index.php/pilot-information/joining)

[Tony Mabelis]

There have been several collisions with vehicles at Redhill over the years.
Its no more dangerous than any other airfield...........if you keep you wits about you and look where you are going!
Tony

[M-ONGO]

I am deliberately playing devils advocate here simply because I see a growing tendency on these forums to jump to uninformed conclusions ( the worst are the drunk pilot threads!).

Most threads now appear to be of the kangaroo court variety unfortunately. Taking a balanced view once all the facts are available is something we can relate to during (some of our) days at work on the fd. Shame some can't carry the philosophy over to these forums.

[Ringway Flyer]

As a PPL and also a radio control model flyer, I have seen at first hand on the model aircraft how little impact is needed to damage a wing. (I had a wing fold part way round a loop, following an earlier heavy landing, with no visible damage).

I'm sure someone more erudite will correct me, but I understand that lifting an aircraft by its wings for maintenance has to be carried out at specific points, designed for the purpose. Lifting at the wing tip, especially 'suddenly', is surely likely to cause damage, as the load is not distributed. No doubt the design of the wing will determine if it's still flyable or not.

RF.

[englishal]

I believe that with a metal wing spar the danger is less, as metal tends to deform and so damage is more apparent. Wood (and presumably composite materials) doesn't and so you could have no deformation but quite some damage hidden.

I am sure there are exceptions, but presumably this chap assessed the impact and deemed it safe to fly the aeroplane after a thorough inspection??

[Dave Gittins]

The general position with any structure is that for reasons of economy (eastern European tractors excepted) their strength lies in the direction in which they are designed to carry their forces or loads.

In other directions they can be decidedly easy to damage by applying a load for which they were not designed and which the certification (or design approval) permitted.

If an incorrectly applied (or correctly applied but excessive) loading occurs, it is always essential to have an appropriate inspection by a suitably qualified person before further use.

I can recall such things as DC-10 engines removed from the aeroplane in an un-approved way with a fork lift truck.

[Blink182]

Why wasn't the van wearing a Hi-Viz jacket ?

We all know that simple H and S regulation would have prevented all of this :rolleyes:

[mad_jock]

Wings arn't designed to take a point load at the wing tips.

I am sure G or IM have the proper data but i would have thought as an ex structural engineer.

The design is for a force loading over the length of the wing design so even if you don't take into account the washout as you get near the tips you can simplifiy that to a point halfway between the support and wing tip. In actual fact it will be alot closer to the support which makes matters worse the nearer the support it is.

Now the support will act as a pivot point so the moment applied from one side with counteract the moment from the other. So in flight the moment acting on the pivot point will be reduced.

By point loading the tip you have doubled the moment acting on the pivot point (in real life it will be more). Yep great the plane is rated at 3g so that not a problem but then you don't have is the balancing moment from lift from the other side of the pivot point. Then the bit of wing inside the pivot point is subject to a negative moment 3 times as a guess more than its designed for which is of course -1g. Then the wing mountings are also getting 3 times more in the wrong direction as well.

Metal doesn't just break when you hit its limit. It has a linear load profile up unto its yield point. Which means it will go back to where it started when the load is taken off, then a nonlinear responce until it fails.

Stress (http://en.wikipedia.org/wiki/Stress%E2%80%93strain_curve)

It could very well be the metal has deformed but not to notice. So what you might say.

Then we get into strain hardening.

Work hardening - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Strain_hardening)

Again so what.

Different strength metals next to each other act as a stress concentrator which means that it acts as a focal point for fatigue cracks to occur.

I reckon it could be a time bomb, it might also not be picked up in a normal inspection unless the engineer knows the history and is looking for it. Until some one sits down and runs the numbers nobody will know. And you certainly wouldn't know with a quick walk round.

Quite alot of industrial failures are caused by none designed loads which have occured while in transport. In fact one of my collegues from my degree course all he does is design loading jigs for transport. And unless the transport jig is certified by DMV etc the equipement ain't allowed to be used.

Now I haven't practised as an engineer for quite some time and I don't have a FEA package to play with or a copy of Roarks. So if this thinking is a pile of poo please correct it.

O and I haven't even started on a point load in the laterial direction

[abgd]

Until some one sits down and runs the numbers nobody will know.

How would an engineer go about determining whether the structure was safe, following the application of an unknown load? I can see how you can do this for an Airbus which has all kinds of accelerometers and stress-meters built in, but short of finding the van again and recreating the accident, I don't see how you're going to get the numbers to plug into the analysis. Perhaps light aircraft should start carrying some of these monitors (complexity, groan...) as they could probably be made quite light and cheap nowadays.

In hang-gliding we always used to inspect the spars for wrinkles or dents following a 'whack' or crash, and that was about it. Hang-gliders are abused substantially yet structural failure is very rare.

For this accident, I find it interesting that the pilot didn't seem to notice it. At the end of the day, if you push against a wingtip you have a huge amount of leverage and if the wing rode over the van without causing the pilot to require substantial amounts of differential brake, I can't imagine the forces were terribly large?

Even if the pilot did require substantial brake, there would be a limit on how much force he could apply through the wheel, which I guess could provide some measure of the force on the wingtip. Perhaps I'm answering my own question..?

[mad_jock]

Opps sorry just realised your completely correct but I will leave the post anyway. I was on day 5 of 6 sector days on earlies.

The youngs modulus doesn't change and after yield there is residual stress in the structure and the hardness changes. It is one of the of the ways you test that something has yielded. And as the metal becomes harder it becomes more brittle which effects its post yield behaviour.

For abdg, its a rockwell hardness tester PCE-2000 (type D impact) hardness tester (http://www.industrial-needs.com/technical-data/hardness-tester-PCE-2000.htm) that we use and the change in hardness tells you how much its yielded by. You can also acid etch the surface and look at the metal grain. And if you really want to get fancy you stick a x-ray diffractometer on it and that will give you a real reading of the residual stress in the metal.

Basically the stress strain curve shifts to the right but it never returns to the original zero strain. The yield point increases which is sometimes used to work harden for use so the strength is increased. The classic example of this is high pressure piping systems and the teeth on digger buckets. Both cases the metal is quite mallable when installed but after the work up in the pipe system and using it after the install the metal properties change allowing alot higher pressures to be carried. The digger teeth you can grind them and weld them before using them but after a couple of hours work you can't touch them with a grinder and if you weld them they will just shatter.

For a given load you first have to over come the residual stress then you will start deflecting. The material next to that will be deforming as it did before which will set up a discontinuity which will act as a stress concentrator.
So if you deflect a yielded bit of metal by say 5mm it will require a different force to deflecting a none yielded bit of metal by 5mm. So I would call that a change in stiffness but to be honest its more a discussion on definitions than anything else and the US engineers do use different terminology to european ones.

Stiffness - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Stiffness)

[John R81]

ABGD - you think he may not have noticed?

Take a look at the end photos on this site, where some youths are standing by one they built. Rans Build Pages (http://www.flyers.org.uk/Activities/BaP/BaPBuild/BaPBuild.htm) [This aircraft has nothing to do with the incident, it is just a good photograph]

I don't know the clearance under the wing of a Rans 6, but I do know that youths are rarely available equal to the height of the van roof - 2225mm. The contact point was not on the wing tip, but approx 15cm inboard from there. You will appreciate the angle of bank that creates for the Pilot, which continued for the length of the van. When the wing "fell off" the van rear, the Rans lurched to the right so hard I thought the Pilot was pulling over. The Rans wheels left the taxi-way and the Pilot corrected for that and rejoined.

The impact left red dye from the Dacron cover along the edge of the van roof.

The pilot "did not notice"? If that's true, how can he possibly fly the aircraft! His sense of balance is shot, as is his observation of the horizon / bank angle.

It seems likely that you will read more about this event in later months.

[abgd]

Thanks Mad Jock...

So you do the tests, then presumably use the FEA to work out how much the initial strength of the spar has been compromised, and whether it's still got an acceptable fatigue life ahead of it?

[mad_jock]

What a cracking project for the youngsters to have done.

It seems likely that you will read more about this event in later months.

Seems like someone has taken an interest then. It will be interesting to know what the engineering report is afterwards.

How fast was it going?

So far we have only spoken about a static lift of a wing tip. Add in speed as well and the forces applied go through the roof.

You tend not to use FEA like that unless your doing an experiment to find out whats happening. Then you are using the data to tweek your model so you can predict whats going to happen with other loads etc. Once your into yield points and large deflections your into nonlinear FEA which was my skill set.

The linear side of things is pretty much intergrated now into all the CAD packages and will spit out some very pretty pictures. It was just changing as I was leaving engineering. I hope things have improved since then there was alot of people using it that didn't realise that von mises stress is always positive and not really a real stress and only of use for working out the failure point. Which led to some interesting designs. And they would force solutions through with "ill conditioned matrix" errors. I am sure though that the software packages have got more protective so instead of ill conditioned matrix the error is now "your boundary conditions are a pile of ****e" instead.

What are von mises stresses exactly in laymans language? - Yahoo! Answers (http://answers.yahoo.com/question/index?qid=20070805164332AAvCDof)

Most engineering is done by reference to codes and the codes will have acceptable limits and if your outside that its scrapped unless you can do a full analysis. Huge structures which are worth it then tend to get instrumented with strain gauges in high stress regions . They will then take a series of zero load readings then ramp the load up and see how the structure responds. Give it a dynamic wack to seem what its frequency responce is like. There are engineers that can tell you all sorts of things about whats going on by the structures natural frequency. Then basically they monitor it and watch for any changes.

Its actually the fun side of engineering which is quite specialised, completely different to the office code bashing side of things.

And yes thats about the sum of it in laymans terms but there are only a few structures out there that they do this for. The prime example is a nuclear reactor which they check ever 6 months or so to see whats changed. But that has alot more factors effecting the metal than just load. You have load creep, Neutron creep, thermal gradient effects and no doudt more that slip my memory (its been 20 years since I did that course at uni)

[John R81]

Taxi speed - walking pace? Wing impact to the sloping front of the van

[abgd]

John_R81...

Your initial post didn't have most of that information, and I got the impression that the wing just rode up a few inches then dropped down again - not that the pilot was fighting to keep the aircraft on the taxiway.

I don't find your pictures terribly helpful, because I don't know how tall the van was other than that it was 'a few inches' higher than the tips of the wing.

'A few inches', as you originally stated, applied to a wing half-span of 5 metres wouldn't have produced more than a degree or two of bank which the pilot may not have noticed, or could have ascribed to unevenness in the taxiway. From the fact that the aircraft lurched to the right after the (presumably) left wing dropped implies to me that the pilot was probably using a lot of right brake, and therefore must have noticed that something was wrong. I assume the conditions weren't gusty on the day?

[John R81]

Not gusty at all. Van height stated in the post with a link to the pictures. If someone can share the wing clearance of a Rans S6 it would help.

[goldeneaglepilot]

Hi John, Please see email re this incident (just sent to you)

[mad_jock]

S-6ES Coyote II Aircraft Kit (http://www.rans.com/aircraft/kits/s-6es-coyote-2.html)

So 7'4 if its a trike or 6' if it was a tail dragger.

Usually the compact vans are under 6 ft so they can get into car parks.

But I don't doudt your description of the wing getting lifted.

[abgd]

Well, it certainly sounds as if he should have noticed...

I think it was a point worth clarifying though.

The engineering does sound fun, MJ. Methinks I shall have to sit down and read up on it a bit more.

[mad_jock]

It is bloody good fun but unfortunately very specialised and hard to get into.

O and the reason why they monitor the frequency is they can tell when a crack is starting by the frequency signature and then how far it has extended by the change.

[John R81]

OK - I understand 350mm too short to go over the van. The van is a good deal over 6ft high. I am 5ft 11 and I needed to stand on to the van floor to get height to see the witness marks.

Mad Jock - I think your nmumbers are total height which for the Trike would be top of the tailplane (it was a trike). For the tail dragger the height would be for top of the wing leading edge or cockpit so you would still need to subtract the depth of the wing to get the clearance. Clearance for the trike I understand to be 1875.

John

[abgd]

It is bloody good fun but unfortunately very specialised and hard to get into.

Especially when you studied medicine.

Seriously, if anybody can suggest any good alternative careers for a technically minded medic, I'm open to suggestions!

[mad_jock]

Well actually there are specialist engineering courses for medics. Mainly run by Bio engineering university units round the country. Some medics do them as a Phd in bio engineering and others do them as a MSc.

FEA is used alot in orthopedic implants.

You start off with this.

http://www.biomechanika.cz/pictures/302.png

Then you test it with this.

http://www.biomechanika.cz/pictures/301.jpeg

Bio engineering FEA is a bit of a bitch to be honest though. Virtually all the material properties are non-linear and every bone is different. For all its challanges it also is bloody good fun. I think mainly because you have to verify by experiment then loop back to regig your engineering and then try it again.

And medics especially surgeons who have engineering savy can make a whole heap of money. I met a ortho surgeon who also had a full BEng who had been told that it was a bit late in life etc to be studying medcine, but he was banging out the patents much to the disgust of all his consultants. They were very good designs as well with high success rates and minimal fannying around getting them approved. He apparently was **** hot with a knife hammer and power tools in theater as well.

Then you get into replacement limbs and stump grips etc. Not as much money in it but they all seem to have a good time of it with alot of job statisfaction getting a better quality of life for the person.

One of the medics at Gatwick is right into his modifcation engineering to aircraft for disabled pilots.

[abgd]

Hmm... I'll have to look into that... I'd always thought of it as being medical-physics territory but it seems I'm wrong. I already have a PhD in neuroscience (colour perception), but could really do with more mathematics.

It gives insights into odd things such as the best form of lighting to do medical procedures under, or colour-vision in aviation, or slight improvements to 3d endoscopy... Part of the problem is that when you're working very long hours it's very difficult to innovate, even though I have a few ideas that I would otherwise pursue.

Was your orthopod acquaintance working in the UK or elsewhere?

[mad_jock]

UK , I met him at an engineering conference but it was 15 years ago now. BUt I suspect he is abroad now working for surgicraft or the like.

The bio-engineering units sometimes have a medical-physics attached or they are attached to or they don't. Some have quite a large cross discipline groups from Medics right through to software engineers, or they are just a load of engineers depending where there focus is.

I wouldn't be suprised if you could find something that would allow you to combine the vision stuff with engineering. For example the robotics for nuclear decomissioning etc.

Its one of the good things about engineering if you enjoy it. You can get something between Finance and law right the way through to flying planes or high energy physics experiments.

[Genghis the Engineer]

Brunel Institute for Bioengineering (http://www.brunel.ac.uk/bib)

Some quite interesting stuff going on there within mixed teams of gingerbeers and quacks.

G

[Charles E Taylor]

Perhaps he should send his aircraft here.......It looks like thay have all the tools to test it thoroughly.

The Siberian Research Institute Of Aviation >> TotallyCoolPix (http://totallycoolpix.com/2012/05/the-siberian-research-institute-of-aviation/)



Fascinating



Charlie

[mad_jock]

Now that is hard core engineering porn.

[flybymike]

Jock, no cynicism intended. I have been seriously impressed by your last few posts. Have you been on a spelling and articulacy course? ;)

[mad_jock]

No nothing changed, would be great if it had though.

[flybymike]

Not at all, I rely on your incomprehensible Scottish outbursts to keep up the amusement value in this place;)

[stickandrudderman]

I like A and C's stance on this.

"Nobody shall stone anybody until I blow this whistle!":D

[mad_jock]

Anyone know if the airframe has been looked at?

I am quite interest to know if there was any damage purely from the engineering side of things.

[John R81]

This aircraft crashed at Redhill 28th August, one fatality. Not the same pilot, who left the group.

Pilot dies after microlight plane crashes at Redhill Aerodrome - Get Surrey (http://www.getsurrey.co.uk/news/local-news/pilot-dies-after-microlight-plane-5797138)

Better cover with photo

BREAKING NEWS: Plane crashes at Redhill Aerodrome | This is Surrey (http://www.thisissurreytoday.co.uk/UPDATE-Plane-crashes-Redhill-Aerodrome/story-19717931-detail/story.html#axzz2dGzvklTu)

No idea of the cause, or whether this bump was connected. The aircraft has been involved in earlier accident reports. Registration withheld for the time being.


RIP

[paulc]

Back to the original point of this thread - saw a plane roll down an airifield slope and hit a car that was parked airside. Fist sized hole in fibre glass engine cowling and nose gear spat dented. Pilot proceeded to fly it home. :mad: