C-GISM

[flyinhigh]

Saw a photo the other day (Wednesday) of this Navajo in berins river on a trailer with alot of damage and engines removed. Looks like it was bellied in, does any one know what happened?

[Chuck Finley]

Good job or Variable tailwinds.

[vrrotate]

Well if no one was hurt and the pilots learned a valuable lesson who are we to be asking questions? Best to just leave it to the company's internal SMS no?

[Heliian]

The must have rubbed it out.

[ogc]

Saw a photo the other day (Wednesday) of this Navajo in berins river on a trailer with alot of damage and engines removed. Looks like it was bellied in, does any one know what happened?

CADORS says loss of directional control on the take off. Rejected take off and went off the end of the runway.

No injuries.

Great rego though... I hope another plane gets that one.

[jschnurr]

Where is the CADOR you speak of? I did not see anything.

What I heard was the aircraft was empty (no pax/cargo) and the pilot didn't get airborne in time. Here's a pic of it off the end of 09 in ybv. Airport manager said the left and nose gear were sheared off and there is a 1 inch crack in the right wing root.

10509597_932639513054_9106624156785855283_n.jpg (22.95 KiB) Viewed 4364 times

[CD]

CADORS 2014C2339

UPDATE: TSB Report# A14C0087: The Interlake Aviation PA-31 Navajo (C-GISM) was conducting a take-off on Runway 09 at Berens River, MB (CYBV). Prior to attaining flying speed, directional control was not maintained and a rejected take-off was initiated. The aircraft overran the runway along the centreline and came to rest approximately 400 feet past the turn-around bay. The aircraft sustained substantial damage. Both propellers were intentionally feathered prior to exiting the runway surface. The pilot, who was the sole occupant, exited the aircraft through the rear exit with minor injuries.

[flyinhigh]

Thanks CD,

I was unable to find the Cador myself.

[Big Pistons Forever]

BTW if the CADOR is true IMO the pilot made a poor decision in feathering the props prior to departing the runwy surface. He should have just pulled the mixtures all the way back to ICO.

Much more damage will be done to the engines if the props dig into the ground in the feathered position vice the fine pitch position. You will also get some extra drag from the windmilling prop until you are slow enough for it to stop.

[frozen solid]

Much more damage will be done to the engines if the props dig into the ground in the feathered position vice the fine pitch position.

Is that so? Of course: that's because the props are more bendy in fine pitch than they would be in FX, right? I never thought about it before but it makes perfect sense now that I think about it. Interesting little tidbit, BPF.

[Sulako]

Much more damage will be done to the engines if the props dig into the ground in the feathered position vice the fine pitch position.

Is that so? Of course: that's because the props are more bendy in fine pitch than they would be in FX, right? I never thought about it before but it makes perfect sense now that I think about it. Interesting little tidbit, BPF.

I also never considered this. Please elaborate, I'm genuinely interested.

[digits_]

If a prop bends easily, you will quickly damage the prop, but the engine will be relatively unaffected.

If a prop can not bend, the full impact will be transferred onto the engine crankshaft etc.

A feathered prop will act like a plow, it will plow through the ground and be strong because the impact is at it's "smallest edge". Like what happens when you cut your finger at the side of a piece of paper.

A fine prope will bent as soon as it touches the ground, like what happens when you fold a piece of paper to put it in an envelope.

[trey kule]

That is one of the most interesting things I have read on here in a long time. Still thinking about it.
Do any flight manuals recommend this?

Btw...the pilot may have pulled the mixture and feathered the props. It does not say, but I would expect if he had the presence of mind to feather the props he probably also pulled the mixtures controls. Just a guess though.

[GyvAir]

I've seen the effects of what digits_ is describing. When the nose gear collapses and the props plow deep into the ground in feather, rather than bending back and skiing (for sake of a better word) over top in fine, the forces transmitted and resulting damage are substantial, not just on the engine, but to the engine mount structure, firewall, etc.
Picture a steel scale or ruler.. takes nothing to bend it across the wide profile, but nearly impossible to bend it across the narrow.

[iflyforpie]

I heard the same thing from and old engineer years ago. Not sure if it is hogwash or not but it makes sense. He said that the perfectly stationary blades dug in on one plane he rescued and snapped the crank cleanly off.

Unless you can feather and clock the props to clear, just leave them alone. Insurance should be paying for it anyways.

[trey kule]

While we are talking of procedures. One of the things we were taught in primary training, if facing an overrun was to retract the gear. Less chance of the plane flipping (nose wheel planes). Slows down quicker on its belly. I never had the opportunity to test the lesson, but all the overruns posted here the pilots leave the gear down.

[iflyforpie]

Not sure how that would work with a squat switch. My squat switch is on the nose, but those mains ain't moving with weight on them.

Every overrun I've seen with gear down, the gear snaps off before the plane flips.

Conventional gear..... do a ground loop. Really good at reducing stopping distance.

[sidestick stirrer]

I thought the propstrike damage to the engine depended on how quickly the rotating mass within it was brought to a stop. What is curling those blades is the momentum of all the rotating bits in the engine and one of them is really heavy.
My logic makes it seem that a fine-pitched blade taking a tiny bite of whatever as it is forced below the surface during a few degrees of its rotation would have less braking effect on this mass than the huge increase in area presented by a feathered blade.
I was thinking of trying to plunge a spoon into the ground while pulling it towards me, with the bowl of the spoon facing me versus facing ninety degrees to the direction of pull.
Also, my thinking was that the enormous flat-plate area of a fine-pitched propellor -whether windmilling or being driven by an engine at idle rpm-creates a lot of drag, drag that will help slow the airplane more quickly and reduce the distance it will travel off the runway before coming to a stop.

[Edo]

Insurance is already buying new props, who wants to "save" the engine the have to fly the fucker again after it makes tolerance for crank damage

[Big Pistons Forever]

Insurance is already buying new props, who wants to "save" the engine the have to fly the fucker again after it makes tolerance for crank damage

A full engine tear down and inspection after a prop strike on Lycoming's is mandatory per an AD, not to mention common sense. If anybody just slaps new props on an engine after a prop strike on a commercial airplane and puts it back on line, it is time to drop a dime to TC.

[Edo]

i agree. not suggesting that but Id rather have a fractured crank at inspection rather than one that didnt get bent and goes back into the engine. Deductable will be the same

[Glasnost]

Once they NDT and dial the crank, it is as good as any green tagged one.

[CpnCrunch]

i agree. not suggesting that but Id rather have a fractured crank at inspection rather than one that didnt get bent and goes back into the engine. Deductable will be the same

What about the possibility that in both cases the engine components are within limits? Are you sure you still want to do slightly more damage to an engine that you'll be flying with? I'm not entirely sure your logic is sound, although I've never had a prop strike (or any accident for that matter).

[Edo]

I guess Im not being too clear here. I would make control selections based on the AFM procedure and in the absence of a specific prop selection (feather or fine) then do whatever would stop the aircraft sooner and mitigate possibility of fire.

Good discussion points on damage associated with feather / fine but Im not gonna base the decision on less damage to the airfcraft more on survivability for pax and crew. cars have crumple zones for a reason and so do some aircraft. In this case feathering the props isnt gonna make you stop sooner. Following an something like this incident with no injuries, broken props and broken cranks are icing on the cake, get new ones and get her back online dont try and fix broken shit....im paid by the mile

[PilotDAR]

If you're going to hit a prop on the ground, don't feather it, for the reasons well given. It's wrecked in any case, but maybe sacrificing the prop, can prevent or reduce damage to the engine or airframe.

If you have to "crash" into something, I'd rather do it going forward. The aircraft is designed to restrain occupants for a 9G forward crash force, but only a 1.5G sideward force, and no factor rearward. If you groundloop, or otherwise change direction so that you hit not going forward, you greatly increase your chances of injury.

There comes a point, where a plane is going to be wrecked. If this sad outcome is certain, then use the plane to protect the occupants, by allowing it (or causing it) to absorb energy progressively.