Observations on the Croft Farm incident.
I hope this post on my observations and thoughts on the event will be of some use. Hopefully it will help confirm or refute some suggestions already made and add to the knowledge of what can be done to minimise or prevent this incidents in future.
Observations, background and what we witnessed.
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Croft Farm is a small, well looked after, unlicensed farm strip in the heart of Worcestershire (UK). In fact it is Worcestershires largest active 'airfield' as the county is very poorly served for aviation needs. The link should give you an overhead satellite view of the strip. If not, it's a mile or so west of the village of Defford, just south of the old RAF airfield (disused for flying), now a comms base.
http://maps.google.co.uk/maps?ie=UT...pn=0.005617,0.014462&t=k&z=16&iwloc=addr&om=1
An annual fly-in was in progress, an event which has become increasingly popular with both flyers and public over the last few years. The weather was warm, sunny and with little or no wind. The ground in the public walking areas was firm and the grass was not wet. The strip itself appeared recently mowed and looked in good condition (as viewed from the public areas). Plenty of aircraft had taken off or landed at the strip that day without incident.
With reference to the map link above aircraft were using runway 10 (from left to right). My father-in-law and I had recently moved positions, setting up just to the right of the 'indent' where the facilities are. This is about two-thirds of the way down the strip in the direction of use. I had just left this spot, heading to the right of the map, to get photos of aircraft parked in the static. G-CDRM was briefly seen passing directly past me between two parked aircraft - I noted it appeared to be travelling faster than other landing aircraft at this point of the strip. A few seconds before, back at our 'base camp' my father-in-law had made exactly the same observation. We later estimated the speed to be about 30-40 mph, for whatever such guesses are worth. Neither of us saw the approach or touchdown. The aircraft was then lost to my view briefly behind a parked aircraft before reappearing and tipping right over like in the youtube video. Other pilots rushed to the scene immediately and lifted up one side allowing the occupants out. Good and fast work everyone. After the rescue everyone moved back (as one! Honestly, it was if everyone had been training for the incident). At the time the crowd did not know what exactly had happened to the occupants, which was very uncomfortable. There was concern over why everyone had moved away from the aircraft and no-one had been seen getting out - people were fearing the worst. Of course, the occupants were out and everyone then moved back for safety.
I've attached a photo of the aircraft upside down on the strip. The damaged nosewheel and grass in intakes is evident. The actual nosegear appears intact, the break occuring in the fork area.
http://www.airliners.net/open.file/1242940/L/
I estimated that the actual area of the accident is quite far down the strip as the accident occured past me and I had walked away from where we had setup our stuff. Maybe halfway between the 'indent' and the right-hand end of the strip. There did appear to be space to slow down safely however.
In the video, you can see the aircraft travelling still relatively quickly at this point. The video also shows a quick dip before the flip.
Thoughts
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a. The aircraft was moving faster than others at the same point in the landing. Did the aircraft make a late touchdown or bounce? Was a rapid slowdown then found to be necessary? These could have put extra strain on the nosegear, especially on a grass strip. Perhaps the aircraft was simply travelling quicker to vacate the runway for following aircraft? The strip was busy at the time. Whether or not speed was actually a contributory factor in the accident occuring in the first place, it does have an impact on what happens next - that energy has to go somewhere. Incidentally, I am not suggesting that the pilot was at any time travelling at an excessive speed, just that it was higher than other aircraft we had seen at the same point of the field.
b. The dip in the video. Almost certainly linked to what happens next. Could it be the nosewheel entering a pothole? We don't have gophers. I guess rabbits could dig a hole, but I don't recall ever seeing them or their droppings at Croft Farm. It is a grass strip, so the surface is uneven compared to tarmac. I don't think the strip surface is any different than other grass strips, but you'd really have to have some input from those who have flown there. I have witnessed some bouncy take-offs here before:
http://www.airliners.net/open.file/0871385/L/
but generally aircraft have not seemed to be in difficulty with the conditions.
Is the dip not a pothole incident, but the recording of the nosewheel actually breaking? I suspect so, especially as the flip occurs immediately after this point. Photos of the aircraft afterwards show the nosewheel actually hanging on the strut.
After reading your comments on these forums and accident reports elsewhere, I believe the nosegear on the 7a is susceptible to breakage under certain conditions. While this is true of any nosegear, the conditions under which the Van's will break appear less forgiving than most. After breakage, this leaves the nosewheel as a forward pointing stick, which will stick in the ground and flip the aircraft if the speed is high enough, just like an olympic pole-vaulter.
I guess the UK AAIB is investigating this incident, so I'm sure we will see a full and accurate report in time - their reports really are of a high standard.
Fortunately, although they happen, these incidents are still far from commonplace.
I'm not a pilot so can't really offer advice, but the other responses here give some good thoughts. When on grass strips, take extra care generally, check the strip condition beforehand if you can, keep high-speed ground travel to a minimum and check the nose gear for any cracks etc. Consider suitable mods to the gear for improving the situation should the worse happen - even spats may help.
The RV's have rapidly become one of my favourite light aircraft to photograph - sleek and sporty - so I hope you keep building and flying them!
Best regards,
Jim
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