Warbird Information Exchange

Prop Folks:

Good day!!

You are looking at one of two 5 bladed props on a Let 410 that went down tragically with 14 folks (RIP) while on ILS approach at the famous Toncontin airport, Honduras last Feb 14-2011/0745L some 4.5 NM from touchdown.

While the local investigation is ongoing, we kindly request info/comments if the shown prop was turning at the moment of impact or not? Photo La Prensa/www.

Prop Folks:

Good Day!!

Included is a picture of the second engine & prop at the crash site. The Let 410 is a high wing aircraft that struck several trees upon impact with the ground. Photo La Prensa.

Tks in advance for your cooperation.

Do the props automatically feather when the engine quits?

Were the props in the feathered position?

Unless the engines are seized there is likely to still be some very slow rotation on a turboprop.

Look which direction any scratches on the prop blades are angled at.

The Walter M601 is a "free-turbine" turboprop design similar to that of the Pratt & Whitney Turboprops with similar power ratings. The prop is an Avia VJ8-510 which was co-marketed by Hamilton Standard at one point. From the information I've gathered, it operates the same as similar units on the PT-6 being spring-driven to the "feathered" position when oil pressure is removed. Additionally, I found an AD from 2000 in which 2 King Air aircraft had been re-engined with the M601 and suffered engine failures from the absence of several key engine management systems.

Looking at the photos, the thing that strikes me is that all of the blades are reversed to the direction of travel (the de-icing boots are facing away from the direction of travel) yet the bending is in the normal direction of rotation (counter clockwise when viewing from the front). Additionally, the amount of bending seems "light" if the engines were producing significant power.

Compare to this picture of an engine known to be producing power at the time of impact -

http://aviation-safety.net/photos/displ ... =11&kind=C

Also, here is a picture that shows the bending of the props of a feathered engine -

http://aviation-safety.net/photos/displ ... r=1&kind=C

I am not a "prop guy", so I won't make any speculation, just provide the information and observation for others.

BDK/CapFlyer:

According to reports that model had the automatic feathering & manual feature installed provided the overhead panel switch was armed.

We do not know the angle of incidence of this aircraft before it stroke the ground. It was flying in a dense fog with extreme turbulence apprx 35Kts+ at some 4.5 NM from touchdown. It is poss that the blades hit the trees first before the wings came off and then the blades hit the ground.

We'll post more close pictures of the blades & engines as they come available.

Tks for the help, info & data provided.

BDK CapFlyer:

The picture included shows what HR-AUQ crew (RIP) should had seen once out of the fog/ clouds. Unfortunately, The Let 410 crashed some 3.0 NM back south.