Cessna 336 N538JP Crashed in Guatemala

rrice · #1 08-11-08, 01:04 PM

Skymaster 336 N538JP, Operated by the Christian missionary aviation organization Great Commisison Air crashed in a mountainous area of Coban Guatemala while providing an emergency medical evacuation. There were 4 passengers on board.

A mechanical failure, probably related to the flap system, caused a severe split flap condition while approaching the high altitude airstrip in Coban. After applying the last 10 degrees of flap, there was a very loud BANG and the aircraft rolled over on its back to the right. It was completely out of control until the flaps were retracted.

The aircraft was destroyed when it impacted the top of a narrow ridge at a high rate of speed and tumbed end-over-end several times.

Miraculously, there were no injuries!

To read to complete story and see a photo go to: http://GuateMissionPilot.BlogSpot.com

GCA is seeking a donated aircraft to help continue its mission in this very needed area. Many lives are saved on a fequent basis using aircraft to provide medical transport to the very poor in extremely remote areas of Guatemala. Please to to http://www.GreatCommissionAir.org for contact information.

Praise God for His amazing hand in the survival of the pilot and passengers!

Ernie Martin · #2 08-11-08, 01:53 PM

Thank you so much for sharing this with us. It's obvious that you and your passengers are blessed, to have survived this accident. May we ask that you tell us the flight hours on the airframe.

This is the second instance, to my knowledge, of a flap incident like this. It's very fortunate that there have been no deaths. It makes it critical that we all check our flap cables per the published procedure. See this thread for more info and pictures: http://www.337skymaster.com/messages...read.php?t=547

I attended the show-and-tell briefing Don Nieser gave at his facility, and folks, inspection of the cable is not easy if you don't know how to do it.

I am going to ask Don if he would be kind enough to do a 3 - 4 minute video of the procedure so that we can either post it here or on youtube with a link from here.

Ernie

rrice · #3 08-11-08, 02:18 PM

There was somewhat over 5,000 hours on the airframe. Obviously, as a 1963, 336, it had a LOT of YEARS on the airframe, perhaps an even more important issue. If we are fortunate enough to find another 336 like that one, I will be sure to pull ALL the cables out and have them completely inspected, along with the obvious (bellcranks and pulleys, etc). There are lots of places in the complex flap system where problems can crop up.

Don Nieser · #4 08-12-08, 11:08 AM

Robert Rice and Ernie Martin, if the probable cause was the failure of flap cables, that needs to be determined. Robert could you remove the failed cables and quadrant/bell crank assemblies so that they could be examined? Cable part numbers are: 1460100-7 (Inboard) and 1460100-8 (Outboard), 1460100-6 (Return) and 1460100-34 (Return). Quadrant/Bellcrank part numbers are: 142620-11 and -12 (Inboard) and 1426020-1 and -2 (Outboard). see Figure 83. in the Cessna 336 Parts Catalog. The cable part numbers that are single or double numbers after the dash are ordinay steel/iron cables. If the part number is a -3XX after the dash it is a stainless steel cable. I will be glad to help in the investigation.
Don Nieser, Commodore Aerospace Corp. 405-503-4686

rrice · #5 08-12-08, 11:37 AM

Don, Your are correct that it is all speculation at this point. The parts are in a relatively safe place in Guatemala. I need to get some help to take the wings appart for a more complete investigation. That will take some time. Thanks for your offer to help.
As I know more or have more parts, I will update this post.

WebMaster · #6 08-12-08, 02:38 PM

Robert, I am not sure if you know how to get the flap quadrants/bellcranks and cables out of the wings, if it would help I could take some photos and send them to you. With the flaps in the down position, the access panels in the flap wells need to be removed to gain access to the cables and quadrants/bellcranks. The quadrants/bellcranks are held in by a bolt that goes from the top of the wing to a nut on the bottom of the wing. The cables ends are attached to the quadrants/bellcranks. I would look for any evidence of rust "iron oxide"
on the cable wires.
Don Nieser
Commodore Aerospace Corp
405-503-4686
On Tue, 12 Aug 2008 11:37:25 -0400 (EDT) "Skymaster Forum"
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birddog · #7 08-20-08, 11:24 PM

In the event of a broken cable and split flaps, does selecting flaps up return the flaps to a symetric position? Ie will both flaps travel to the up position or does the broken cable flap remain in the position at failure? Would selecting full flaps at a higher altitude have merit as a precation.
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