RV7 Accident NZ

[Super Cub]

RV7 Fatal.

 

Witness said wing separated in flight.

 

Certainly havnt heard of that happening to RV aircraft before?.

 

Im sure many will be waiting for the investigation report, including myself.

 

Killed rescue helicopter pilot a 'fantastic, good guy'

 

 

[flyvulcan]

A tragic outcome. Hopefully the authorities can determine the cause quickly in order to prevent similar occurrences in future.

 

 

[bexrbetter]

The amount of Vans flying with similar wing construction, i.e. near 10,000 of them, makes this an anomaly. Never heard of a Vans primary structural failure before.

 

Either a major mistake while building it, a serious flaw in a material or some sudden extreme G load.

 

 

[alf jessup]

The amount of Vans flying with similar wing construction, i.e. near 10,000 of them, makes this an anomaly. Never heard of a Vans primary structural failure before.Either a major mistake while building it, a serious flaw in a material or some sudden extreme G load.

I think you have the senarios covered there Bex

 

 

[djpacro]

A history of RV structural failures (not suggesting an issue with Vans design or manufacturing):

 

First, a 1998 bulletin from Vans https://www.vansaircraft.com/pdf/saib_faa_rv3.pdf

 

Others since, such as https://www.ntsb.gov/_layouts/ntsb.aviation/brief2.aspx?ev_id=20121126X24312&ntsbno=WPR13FA056&akey=1

 

And this one close to home https://www.atsb.gov.au/media/24397/aair200701033_001.pdf

 

I occasionally get invited to teach people aerobatics in their RV and I take a keen interest in W&B, mods wrt spin behaviour etc before I start the discussion.

 

 

[Super Cub]

Yes. There were a few failures of the RV3.(and were early RV4 also susceptible?).

 

Will do a search for other RV6 - RV14 spar failures.

 

 

[bexrbetter]

A history of RV structural failures (not suggesting an issue with Vans design or manufacturing):

Fair 'nuff, all but one, old RV3 mostly built scratch from plans by the owners, unlike todays kits.

 

None of that sways my opinion on the proven safe number of hours of normal flight flown in RVs. Considering how many average people with no 'Man Shed' experience at all building them, I would say their record is exceptional.

 

I think if you get into aerobatics, you take your chances.

 

 

[djpacro]

RV-8 operated by Vans is one I recalled too https://www.ntsb.gov/_layouts/ntsb.aviation/brief2.aspx?ev_id=20001211X10121&ntsbno=LAX98FA171&akey=1

 

 

[facthunter]

New Zealand is not noted for endless calm days and no CAT. If you go fast you risk "G" loads. Gust loads add to manouvering loads at times Nev

 

 

[poteroo]

New Zealand is not noted for endless calm days and no CAT. If you go fast you risk "G" loads. Gust loads add to manouvering loads at times Nev

I think this is part of the possibilities.

 

The RV7, being aerobatic, has 2 sets of load factors. For 'normal,non-aerobatic flight' - it has the usual +3.8 / - 1.9 load factors. For aerobatic flight, it is weight limited to 727 kgs, down from 818 kgs MTOW.

 

Now this is where it gets interesting. Va is calculated from the clean stall speed at any given weight - and, Vs varies with the weight of the aircraft. So, at MTOW of 818 kgs - Vs = 56kts. At aerobatic weight of 727 kgs - Vs is, (my calcs), 50 kts.

 

Now, VANS states that at aerobatic weight of 727 kgs, the RV7 has a load factor range of +6 / -3 g - higher than at MTOW.

 

So, using the calculation of multiplying the Vs x the square root of the positive load factor to attain Va, I obtain the following:

 

MTOW 818 kg: 1.95 x 56 = 109 kts Va ( which is well less than the blue line on the analog ASI provided ex VANS)

 

MTOW 727 kg: 2.45 x 50 = 123 kts Va (which is the blue line shown by VANS for the RV7)

 

This presents the pilot with a conundrum, of sorts.

 

On the one hand, it appears you could use 123 kts as your Va for all 'normal' flight if the weight was limited to 727 kgs?

 

OR, is VANS saying that, yes, you can do limited aeros if the weight is kept below 727 kgs, and that during those aeros you should not exceed 6G?

 

AND, does VANS mean that, for the majority of the RV7s' usuage, it should be operated in the normal category to a limit of +3.8/-1.9g, because it is not really designed to be aerobatted for its entire life. In which case, it appears that they may have published a Va which is too high?

 

Remembering that the RV7 cruising speeds are way above even the Va of 123 kts, it is entirely possible that the airframe could be really stressed by hitting some really severe turbulence around mountain areas. And, with 180HP and a cruise pitched propeller, it takes quite a few seconds to decelerate to Va - probably too long to avoid some structural effects.?

 

It's also worth checking all the VANS SBs on their website: there have been SBs raised for stabiliser cracks, elevator spar cracks, and the wing aft spar at the inboard aileron hinge bracket. This would prompt me to think carefully about, not just aerobatics, but the cruising speeds to use where turbulence might be expected.

 

Having flown around 1000 hrs on every model of RV, and seen how often pilots flog them downhill with the ASI in the bottom of the yellow arc - I'm surprised that we haven't seen any obvious airframe damage in Australia. I can only ascribe this good result as being due to the inherent strength in the RV series. Love 'em.

 

happy days,

 

 

[jetboy]

poteroo you might like to comment if anything here was out of line

 

Flightradar24.com - Live flight tracker!

 

you can play back the last few days data : it seems to have been doing around 186 kts (groundspeed) and 4500' at the time mode S was lost, roughly overhead the debri field

 

the day before peaked @ 200 kts gs in descent. I think it was a 200 hp installation.

 

 

[Super Cub]

jetboy, good find.

 

I'm sure they will try to determine if the aircraft was doing Aeros at the time of the accident, looking at the playback, it appears not, apart from maybe a level steep turn a little before the tape stops.

 

Hope they determine the cause and publish promptly.

 

Cheers.

 

 

[poteroo]

poteroo you might like to comment if anything here was out of lineFlightradar24.com - Live flight tracker!

 

you can play back the last few days data : it seems to have been doing around 186 kts (groundspeed) and 4500' at the time mode S was lost, roughly overhead the debri field

 

the day before peaked @ 200 kts gs in descent. I think it was a 200 hp installation.

Good find. Having only groundspeed makes interpretation difficult, but I think we could assume that they were in less than 20-25 kts wind at Whangerai, well up the North Island, and in summertime.

 

Now 200kts GS is right on the VNE of 199 - but take 25 off that and its 175, well back from VNE, but still just above Vno - which is 167 for the RV7. So, it's possible they were into the lower end of the yellow arc of the ASI.

 

Now, the Vno is based on structural strength, and is that which allows for up to a 50fps gust. However, it is usually placarded as 'smooth air speed' and 50fps is far from smooth!! But, we don't know whether encountering a 50 fps gust was even likely....probably not.

 

What I'm interested in is the information about the Va speeds for the RV7. The 123 KIAS Va speed usually given for RV7s allows for a 6G load on the aircraft when full elevator is applied. But, this also means the aircraft must be 727 kgs or less to allow this. Any heavier, and perhaps there is real structural risk?

 

Is it likely that anyone would apply full elevator above 123 KIAS? Quite possible if avoiding a bird collision, or perhaps recovering from a loop where the elevator was used harshly to roundout at low level? No doubt the NZ ATSB will follow all the possibilities and we can only keep watch on their findings.

 

I think it does alert all pilots to the fact that aircraft can be overstressed by pilot inputs' and turbulence when flying above Va - and who isn't cruising there? But if you have a particularly fast aircraft, as RV's are, then fly it according to conditions and avoid overcontrolling it.

 

 

[Gravity]

I think this is part of the possibilities.The RV7, being aerobatic, has 2 sets of load factors. For 'normal,non-aerobatic flight' - it has the usual +3.8 / - 1.9 load factors. For aerobatic flight, it is weight limited to 727 kgs, down from 818 kgs MTOW.

 

Now this is where it gets interesting. Va is calculated from the clean stall speed at any given weight - and, Vs varies with the weight of the aircraft. So, at MTOW of 818 kgs - Vs = 56kts. At aerobatic weight of 727 kgs - Vs is, (my calcs), 50 kts.

 

Now, VANS states that at aerobatic weight of 727 kgs, the RV7 has a load factor range of +6 / -3 g - higher than at MTOW.

 

So, using the calculation of multiplying the Vs x the square root of the positive load factor to attain Va, I obtain the following:

 

MTOW 818 kg: 1.95 x 56 = 109 kts Va ( which is well less than the blue line on the analog ASI provided ex VANS)

 

MTOW 727 kg: 2.45 x 50 = 123 kts Va (which is the blue line shown by VANS for the RV7)

 

This presents the pilot with a conundrum, of sorts.

 

On the one hand, it appears you could use 123 kts as your Va for all 'normal' flight if the weight was limited to 727 kgs?

 

OR, is VANS saying that, yes, you can do limited aeros if the weight is kept below 727 kgs, and that during those aeros you should not exceed 6G?

 

AND, does VANS mean that, for the majority of the RV7s' usuage, it should be operated in the normal category to a limit of +3.8/-1.9g, because it is not really designed to be aerobatted for its entire life. In which case, it appears that they may have published a Va which is too high?

 

Remembering that the RV7 cruising speeds are way above even the Va of 123 kts, it is entirely possible that the airframe could be really stressed by hitting some really severe turbulence around mountain areas. And, with 180HP and a cruise pitched propeller, it takes quite a few seconds to decelerate to Va - probably too long to avoid some structural effects.?

 

It's also worth checking all the VANS SBs on their website: there have been SBs raised for stabiliser cracks, elevator spar cracks, and the wing aft spar at the inboard aileron hinge bracket. This would prompt me to think carefully about, not just aerobatics, but the cruising speeds to use where turbulence might be expected.

 

Having flown around 1000 hrs on every model of RV, and seen how often pilots flog them downhill with the ASI in the bottom of the yellow arc - I'm surprised that we haven't seen any obvious airframe damage in Australia. I can only ascribe this good result as being due to the inherent strength in the RV series. Love 'em.

 

happy days,

As you would know also the Vans machines flown high & fast downhill will often go over VNE pretty quick

 

 

[facthunter]

They VANS, have extensive information on record about that. It's a little tricky at higher levels with TAS/ IAS differences, I think that was more about flutter speeds, IF I recall correctly . Vans don't like to see their planes overpowered. If you regard your Vans as a little hotrod, you are more likely to fly it that way.. There's a lot about.. You aren't different when you own one. Nev

 

 

[Gravity]

They VANS, have extensive information on record about that. It's a little tricky at higher levels with TAS/ IAS differences, I think that was more about flutter speeds, IF I recall correctly . Vans don't like to see their planes overpowered. If you regard your Vans as a little hotrod, you are more likely to fly it that way.. There's a lot about.. You aren't different when you own one. Nev

Yes I have been reading a lot on the Vans machines as I am in the market for one. Recently flew a Harman Rocket, stupid power with crazy perf!

 

 

[poteroo]

They VANS, have extensive information on record about that. It's a little tricky at higher levels with TAS/ IAS differences, I think that was more about flutter speeds, IF I recall correctly . Vans don't like to see their planes overpowered. If you regard your Vans as a little hotrod, you are more likely to fly it that way.. There's a lot about.. You aren't different when you own one. Nev

Yes, VANS has put out a short article on this very thing, but with particular reference to the RV9 and RV9A, which are structurally different, and less robust, than the other models. In particular, VANS recommends not exceeding 160HP in the -9 models because of their lower Vno and Va speeds.

 

I understood where he was on this issue, but chose to fit a IO-360 Superior, (delivering more than 180HP), to my -9A. In my defence, I can say that I've always been super conscious of the need to slow down, (in all aircraft), on descent, and whenever there's turbulence happening, or forecast. I have a G-meter fitted and check it after each flight. So far, I've never been near +3.8 - 1.9 and plan to keep it that way.

 

happy days,

 

 

[Gravity]

Yes, VANS has put out a short article on this very thing, but with particular reference to the RV9 and RV9A, which are structurally different, and less robust, than the other models. In particular, VANS recommends not exceeding 160HP in the -9 models because of their lower Vno and Va speeds.I understood where he was on this issue, but chose to fit a IO-360 Superior, (delivering more than 180HP), to my -9A. In my defence, I can say that I've always been super conscious of the need to slow down, (in all aircraft), on descent, and whenever there's turbulence happening, or forecast. I have a G-meter fitted and check it after each flight. So far, I've never been near +3.8 - 1.9 and plan to keep it that way.

 

happy days,

Isn't there a 9A for sale in Albany?

 

 

[rgmwa]

Isn't there a 9A for sale in Albany?

Yes, unless it's been sold in the last few weeks. PM me if interested. I have some information and no doubt Poteroo knows about it as well.

 

 

[Gravity]

Po

 

Yes, unless it's been sold in the last few weeks. PM me if interested. I have some information and no doubt Poteroo knows about it as well.

Poteroo has already been in touch thanks.

Having you guys about is like having 10 sets of eyes looking out for me....lolol

 

 

[RV6JOY]

One RV9A sold last week in Albany and headed East.

 

Still another for sale in Albany. Also one for sale at Jandakot.

 

 

[ave8rr]

I am advised that the Accident RV7 had been covered in a shrink wrap type coating instead of being painted. I had not heard of this technique but is supposed to be popular??

 

Appears this shrink wrap may have lifted and caused a control surface flutter leading to the inflight breakup?

 

 

[Happyflyer]

I am advised that the Accident RV7 had been covered in a shrink wrap type coating instead of being painted. I had not heard of this technique but is supposed to be popular??Appears this shrink wrap may have lifted and caused a control surface flutter leading to the inflight breakup?

That's interesting. Can you tell us who came to that conclusion please?

 

 

[Gravity]

where/are they all 9A's?

 

One RV9A sold last week in Albany and headed East.Still another for sale in Albany. Also one for sale at Jandakot.

[Downunder]

I am advised that the Accident RV7 had been covered in a shrink wrap type coating instead of being painted. I had not heard of this technique but is supposed to be popular??

Popular in the car and motorbike scene.

You can get textured or plain/smooth in many different patterns, colours.(eg carbon fibre look)

 

I was thinking of putting a couple of bands/stripes around my wings....

 

It's very thin and just "stick on"....will mold to compound curves when heated.

 

I can't say I would ever consider it as a primary covering, more like a decoration/ pinstriping thing.

 

I don't really think it would handle serious speeds. Obviously ok on cars....