RV-6 Down due carb icing

[AJ85WA]

Received an article on my news feed this morning regarding a RV6 that went down in September 2014

It was an interesting read and sure hits home as this could happen to anybody! Thoughts go out to family and loved ones.

Hope we can all learn something from it. Fly safe

http://www.atsb.gov.au/media/5747636...nal_report.pdf

[scsmith]

A reminder to practice power-off emergency approaches, so you can do it if/when you need to.
Almost never a reason to extend downwind beyond the numbers if the engine isn't running.

[Malndi]

Having worked as an accident investigator I have an interest in improving survivability through the design configuration of the cabin and associated equipment.

This is an area that I feel a lot of RV's dont do very well and probably reflects a lack of guidance material. So I was particularly interested to see that the report discussed survivability, hoping it might contribute some new learning that we could apply.

Then I read that the rear portion of the fuselage moved forward due to deformation on both sides of the cabin which reduced occupant space and probably also rendered the shoulder harnesses ineffective for upper body restraint. Seems to be an issue outside the builders control. But I would be interested in the observations of structures guys about where the deformation occured.

[Whitman]

Originally Posted by scsmith

A reminder to practice power-off emergency approaches, so you can do it if/when you need to.
Almost never a reason to extend downwind beyond the numbers.

Spoken from a guy with a constant speed prop! If I perch at the numbers, I will land really long with a fixed pitch prop. The -4 is really tough to slow down.

[rvbuilder2002]

Originally Posted by Malndi

Having worked as an accident investigator I have an interest in improving survivability through the design configuration of the cabin and associated equipment.

This is an area that I feel a lot of RV's dont do very well and probably reflects a lack of guidance material. So I was particularly interested to see that the report discussed survivability, hoping it might contribute some new learning that we could apply.

Then I read that the rear portion of the fuselage moved forward due to deformation on both sides of the cabin which reduced occupant space and probably also rendered the shoulder harnesses ineffective for upper body restraint. Seems to be an issue outside the builders control. But I would be interested in the observations of structures guys about where the deformation occured.

I don't disagree with the idea of making improvements to to aircraft with the goal being to improve crash survivability, but I don't think this accident is a good benchmark to start from.
I am not aware of any general aviation airplane where the occupants fair very well after a stall/spin at low altitude.

From the report.... ATSB analysis based on estimates of aircraft speed, impact angle, and energy absorption indicated that the impact forces imparted to the occupants would normally be expected to result in serious to fatal injuries. This statement precedes the findings regarding airframe damage, so my assumption is that they didn't mean to imply that the damage incurred is what changed it from survivable to non-survivable.

Looking at the in air photo and the photos of the airplane, it looks to me like a partial recovery was made because there is little damage to either wing and the airplane did move fwd a ways from the initial impact point. My arm chair guess is that spin to the left began (the airplane was in a left turn) which a partial recovery was made but resulted in a very high sink rate, but not steeply nose down impact. Odds of surviving that are rather low.

Low altitude loss of control is a primary killer regardless what airplane you are flying......

[Tom Martin]

At engine idle a fixed pitch prop will indeed land longer then a constant speed prop. When the prop stops turning, which happens around 100 knots with an engine failure, there is not much difference between a fixed or constant speed prop.
Turn at the numbers, worst case is you land long and run off the end at a survivable speed.
I have had two engine failures with a fixed pitch RV4, and each time I was amazed at the descent rate. The first time I thought, based on engine running glides, that I woul be off the far end of the runway but in fact I landed close to the numbers.
The second time, having learned my engine out glide lesson, I landed in a soybean field with no damage to the airframe.

[aarvig]

Guys, the real takeaway here is that not everyone is going to do everything just right 100% of the time. It's impossible and it's what accident investigators call Human Error. The reality of the situation is that anyone of us could find ourselves in this situation. You have to be on your game...all the time. Eventually, we may find ourselves in the wrong place at the wrong time. The goal of the skilled pilot is to do everything we can to prevent ourselves from getting into these kinds of situations in the first place.
This is a difficult reminder that in aviation we are playing with rules that are black and white and have zero flexibility. It's important to respect that concept every time we get into an aircraft.

[F1R]

On page 7 of the report, from the last paragraph

" During the on-site examination, the carburettor heat control was identified in the OFF position
(pushed in). It is possible that the impact sequence may have depressed the carburettor heat
control. However, surrounding push/pull controls were undisturbed in their pulled-out positions. "


On at least one side by side I have flown the mixture and carb heat knobs were identical in shape and texture. Only the color is different and I have on more than one occasion over the years, pulled the mixture by mistake. Thankfully the autopilot within has always reacted and just pushed it back.

However, the last sentence of the paragraph indicates the "surrounding push/pull controls were in their pulled-out positions. "

I would think at least the mixture SHOULD NOT have been found pulled out.

[Mel]

I know I will get flamed for this, but a C/S prop will NOT glide more slowly than a F/P. It may "help" you to slow down, but if you learn your airplane, a F/P prop can be landed just as short as a C/S.

[DEWATSON]

Mel,

Not flaming....I do want to make a point. If you have the same aircraft in the same situation at the same airspeed, same altitude and same distance from the runway, the constant speed propeller equipped aircraft will land shorter with the same control inputs from the pilot. I agree that the pilot should know his airplane and cause all sorts of drag with slips and skids, etc. to get his airspeed low enough to land. I also agree that a pilot should never turn his back on a landing sight if the engine isn't running. It would be best to land fast and long and run out of landing space than to stall and spin in. Landing long will almost always be more survivable. Just my opinion.