RV-7A down in NZ 01/01/18 - Accident report released

[N184DA]

Originally Posted by iwannarv

With modern EFIS systems we can set VNE as TAS and it will modify redline on the altitude tape to reflect that. But, not all airplanes have a modern EFIS system....

A call to Dynon confirmed that with the D10A, we are out of luck.
No such ability.

Skyview = yes

But I am not ready to ditch my D10A just yet,, so I will keep an eye (as I always do) on my real-time TAS readout.

[sailvi767]

I don’t think in this case the failure was about the IAS verses TAS issue. The aircraft was 44 knots above the IAS limit and this appears to be a low altitude event. It appears to be a very large over speed. Given the usual temps in NZ the last part of the event at 1700 feet IAS and TAS were probably almost the same.
G

[swisseagle]

In Switzerland, we must place a sticker in the cockpit with the text:

Vne: 200KIAS, minus 2kt per 1000ft altitude

This as a "rule of thumb" to prevent such bad cases.

For those with an EFIS that show Vne in TAS, the sticker is not needed.

[BillL]

Originally Posted by KRviator

ZK-DVS, an RV-7 was involved in a fatal accident 2 years ago. The report has just been published by the NZ CAA, available in PDF format HERE.

Thanks for posting this, I called and talked to the investigator soon after this happened and sent them links to the other reports. It has taken a long time for this report to be issued.

The report leaves me wanting for information to definitively prove that the pilot failed before the aircraft. Was there an analysis or testing to show that the rudder flutters? Ever? Even in the other reports? There is no indication of such. There is a consistent failure mode here and it is hard to believe that RV7 pilots (regardless of experience) are more likely to overspeed than RV6 or RV8 pilots.

Reading accounts of this pilot being careful and conservative are consistent with my son's account of him when flying with him a few months before this accident. He certainly seemed to be a conservative pilot and was employed in an aviation job for Air Rescue NZ, as pilot and safety officer among other responsibilities.

I am going to have to read this for understanding about 5 more times.

[grubbat]

Bill, are we up to 7 planes now? For some reason I thought we had 3 or 4.

Originally Posted by BillL

Thanks for posting this, I called and talked to the investigator soon after this happened and sent them links to the other reports. It has taken a long time for this report to be issued.

The report leaves me wanting for information to definitively prove that the pilot failed before the aircraft. Was there an analysis or testing to show that the rudder flutters? Ever? Even in the other reports? There is no indication of such. There is a consistent failure mode here and it is hard to believe that 7 pilots (regardless of experience) are more likely to overspeed than 6 or 8 pilots.

Reading accounts of this pilot being careful and conservative are consistent with my son's account of him when flying with him a few months before this accident. He certainly seemed to be a conservative pilot and was employed in an aviation job for Air Rescue NZ, as pilot and safety officer among other responsibilities.

I am going to have to read this for understanding about 5 more times.

[Foghorn]

Originally Posted by grubbat

Bill, are we up to 7 planes now? For some reason I thought we had 3 or 4.

I read his statement as RV7s are more likely to over speed than RV6s or RV8s.

[Snowflake]

Originally Posted by BillL

... it is hard to believe that 7 pilots (regardless of experience) are more likely to overspeed than 6 or 8 pilots.

For the most part, -6's and -8's have .020" rudder skins and folded trailing edges, and for the most part -7's have .016" rudder skins and riveted trailing edges. So perhaps the same number of people have overspeeded their -6 and -8 tails, and the effect of doing so is reduced because the design is less prone to failure (due to flutter or otherwise).

[Marc Bourget]

By distinguishing the folded vs. riveted trailing edge, are you making indirect reference to the Kutta Condition?

[BillL]

Originally Posted by grubbat

Bill, are we up to 7 planes now? For some reason I thought we had 3 or 4.

I was (now edited) talking about the RV models, but I think we are up to 5 lost. There is one that happened in AZ and did not get much attention, but when finally the report was available, the crash photos showed the empennage the familiar missing VS/rudder and the HS spar was failed. It had been about 12 months between events up to the NZ one, (Dean). I hope we don't see another anytime soon.

[Snowflake]

Originally Posted by Marc Bourget

By distinguishing the folded vs. riveted trailing edge, are you making indirect reference to the Kutta Condition?

No, I was only saying that maybe the folded trailing edge is less prone to flutter, I wasn't speculating why that might be the case. I hadn't considered the Kutta condition because I had forgotten about it, to be honest... I'll have to go back and review my aero texts...