Stearman Accident Report

[Antique Pilot]

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Brandon, MB.

[Mr. North]

Wonder what altitude they were climbing through (and subsequently fell from) when the engine broke off? Lucky to come out alive after that!!

[cgzro]

It was told it was on takeoff and very low thank goodness.

[Antique Pilot]

It was told it was on takeoff and very low thank goodness.

My friend was flying from the rear seat. The engine fell off at about 50'. The aircraft pitched up and continued to climb to about 100' and started over onto it's back. It did a bit of a tail slide and then pitched forward and hitting in a nose down attitude.

I have in my files 2 other accidents where a prop blade let go and tore the engine off at low altitudes. One a Fairchild 71 in 1937 at Red Lake and the other a C-180 near Ear Falls in 1970.

AP

[ahramin]

In these cases do the blades break or the hub let go?

[Meecka]

In these cases do the blades break or the hub let go?

In this case the blade broke.

[ahramin]

So what if anything does an impending blade failure look like?

[cgzro]

i doubt there is a very easy to detect flaw at least by the pilots. The crack would likely be hidden by the hub, or at least flush with it at the point of maximum stress.

Not sure if that was a constant speed prop but a crack in the hub or blade shank can on more modern otherwise dry props result in grease or oil seeping out down the blades and getting flung on the plane. For an acro plane if we see any grease on the windsreen or oil mist in flight it warrants a quick landing. Those older planes fling oil and grease everywhere anyway so it would be a challange to detect without regular diasssembly and magnaflux.

One other area that can be a worry is oil leaking out the front crank seal when the seal is otherwise in good shape.. Implies oil seeping through a crack in the crank.. Very not good.

As a result my preflights include looking at blade to hub interface for oil/grease and running a hand behind the flywheel.. Not likely to have helped in this case however.

Anybody that saw that plane would say it was absolutely pristine.. Probably one of the cleanest planes in the Vintage Wings collection.

[AirFrame]

This is why aerobatic planes have stout cables attaching the engine block to a hard point on the firewall... As a backup in case a blade fails and the engine shakes itself off the mount. I can't help but wonder if it wouldn't be a good idea on most piston singles.

[cgzro]

ive heard about this but never seen it done and Ive seen a lot of acro planes.

I guess the problem would be a motor swinging one blade hanging on a foot long cable could be a pretty frigging dangerous cuisinart compared to letting it go and using a parachute.

Fellow in Vermont lost a blade and engine last year, he had to bail out. Luckily it happened fairly high up. Would not be survivable at airshow altitudes.

I suppose in this case it could have helped but there is always the question of where the CG ends up anyway because its going to shift aft substantially anyway.

[AirFrame]

ive heard about this but never seen it done and Ive seen a lot of acro planes.

Really? Maybe i'm wrong, I thought it was a requirement for competitions... I've believed that for years?

I guess the problem would be a motor swinging one blade hanging on a foot long cable could be a pretty frigging dangerous cuisinart compared to letting it go and using a parachute.

I suspect if the engine came off the firewall, there would be enough things come loose that it wouldn't keep running long, but I do see your point. I would hope the CG stays far enough forward that full forward stick could keep the plane level, but I haven't done any math to see if that's realistic...

[cgzro]

requirement for competitions

Not to my knowledge and Ive been a tech inspector at a few contests. However redundant seatbelt attached to different points in the aircraft than primary seat belt is the only one I am aware of along these lines. Otherwise they just want to see basic legal paperwork.

Of course a parachute is the main required catch all bit of safety equipement.