ATSB prelim released for RV4 crash at Clyde Vic

[QNH1013.2]

http://www.atsb.gov.au/publications/investigation_reports/2007/AAIR/pdf/aair200701033_prelim.pdf

Makes for some interesting reading on what NOT to do.

[YesTAM]

Confirms what I was told the day after the event - massively over weight.

[Squawk7700]

It's hardly a competition pal.


I'm interested in the 'limited aerobatic' rating gained in 4 hours.

[Wizofoz]

I believe Rans aircraft were banned from Aerobatic competition in the 'States becaus of lousy spin characteristics.

[sir.pratt]

does it run to more than page 9 at this stage?

[Squawk7700]

It doesn't need to go more than 9 pages, everything you need is there...

[J430]

WIZOFOZ

Do you mean Rans or Vans? Easy mistake I guess but two different makes. I believe this was a Vans RV-4.

Cheers!
J:ok:

[Chimbu chuckles]

Wiz my understanding is that they are VERY difficult to hold in a spin. I have not flown them but someone I know who has suggests that, almost no matter what you do, the spin transitions to a steep, nose down spiral dive after a turn or two.

I would think this is a reasonably good general design characteristic if properly understood. The fact that even though grotesquely overloaded the CofG was within normal limits, if not aerobatic limits, suggests a very wide CofG envelope...perhaps leading to a fairly forward CofG generally which would tend to make the aeroplane harder to spin properly. From studying the design and reading the designers words (I am keen to build an RV7 one day) this comes from a very wide chord wing.

The aircraft has a light wing loading. Roll control is described generally in RVs (including by the designer) as 'fairly neutral', 'light' and 'delightfully responsive'. The aircraft is clearly aerodynamically very clean and they usually have high power loadings around 10lb/hp.

Va on most of the RVs is around 140mph (note mph) and Vne just over 200mph.

Sounds like he spun out of a misshandled stall turn, the aircraft quickly assumed a steep spiral dive (known aircraft characteristic) he applied power (god alone knows why) and he was over Va in a flash and Vne a few flashes later...still spiral diving. The spiral dive was described as 'unstable' probably because the pilot may have been a little heavy handed with the controls and frightened himself a few times nearly blacking out. Remember how 'delightfully responsive' the aircraft is.

G, probably made much worse by 'rolling G', tore the aeroplane up and it became a lawn dart.

Rvs are great aircraft and by all accounts very easy to fly for a taildragger...about the same as a Citabria...but you can still kill one from innexperience/ lack of understanding.

[Squawk7700]

I was more of the impression from friends that fly them that they are hard to get *out* of a spin...

Have a mate that entered a spin very high up in his RV6 and got out very... low down... to put it into perspective. He said he only managed to get it out of the spin by heavily manipulating power and even then it wasn't easy. This came from an experienced commercial and aerobatic rated pilot, but admittedly not at competition aerobatic level.

Vans don't allow spinning in some of their models, including the 6, however this trait does flow through the range even slightly so I'm not surprised if other models behave similarly.

Either way 100+ kilo's over weight it quite significant and should never have been attempted.

[J430]

Hey chuck,

wanna go halves in an RV-10?

J:ok:

[Chimbu chuckles]

Now there is a plane:ok:

7700...back in the early 80s I had the same experience with a C152...you'd hadly describe them as a type that is prone to that sort of thing. I started at 3500 agl and ended under 500 agl...trying everything I knew all the way down.

I know not of the spin charachteristics of the RV6...but these people were in an RV4...and they apparently share the RV3's penchant for falling out of a spin into a spiral dive unless you work VERY hard at keeping them spinning...like crossed controls and power.

The RV6 shares the same wing as a RV4 but there the similarities end I would think. I'll ask one of my work collegues if he has spun his RV6...he may not have.

Of course we are dealing with homebuilt aircraft...so the characteristics might vary from one to another...particularly overweight.

It hardly matters...because they were not spinning they were spiral diving. Do what that pilot did in, essentially, any aeroplane and the result will be the same. The RVs are strong aeroplanes...+6/-3 design loads and +9/-4.5 ultimate loads. Not many aeroplanes can sustain high G or lower (but) rolling G in a power on spiral dive well over Vne. In fact I cannot think of one.

Very sad non the less.

[Buster Hyman]

Some people learn to fly without the passion of aviation in their blood & sadly, this is just one of the things that can happen when you don't respect your environment.

:(