C336 Windshield Strap Removal - Help

Alfonso · #1 11-14-05, 07:39 PM

Has anyone used FAA Form 337 (Major Repair and Alteration) to justify the removal of the center strap from the windshield of Cessna 336 or 337? I am replacing my C336 windshield with a new one of 3/16 thickness (same size as before) from Great lakes Aero Products, but there is not STC to remove the center strap. Great Lakes said they have an STC for C182 and C210 that requires the drilling of holes through and on the top of part of the windshield, but the Skymasters do not need that because they already have those holes there. The center strap only holds the compass, the GS antenna and the temperature gage, and it is NOT attached or bolted into its upper or lower part of its frame to support the contention that it is structural. It appears that this is a simple A & P sing-off of minor maintenance, and it is not mayor maintenance that requires FAA Form 337. Can anyone help me out with any feedback on this issue? I heard that some Skymaster owners have replaced it with the approval of an FAA Field inspection. I also heard that they have used a Form 337 to justify doing it, and that if I can have a copy of someone's Form 337 done it, the FAA should approved mine without any delay or problem. Thank you very much for your help. I am waiting for your replies while replacing of the windshield. If anyone is willing to fax me a copy please fax it to 304-255-3688 or at my home 301-934-2111, OR EMAIL: fiestair@erols.com. Thanks, Alfonso

Ernie Martin · #2 11-14-05, 07:55 PM

Don't do it. There is an STC for doing this as part of a kit to provide the added strength to the windshield lost from removing the strap. See www.rtaerospace.com for details. My recollection is that the strap is there for structural reasons, not just to support the compass, and I think that GMAs was a strong advocate of not taking the strap off. If you do a "Search" on this forum, you might find prior discussion on the subject.

Ernie

Roger · #3 11-20-05, 07:52 PM

I checked with Cessna several years ago about the strap over the windshield, as I had to replace one on my 337E. I was told that the problem was that over 180kts, there is a negative wind load (or suction) generated over the windsheild, that makes it want to pop out.

Therein the STC was for a half circle at the top of the windshield to hold it in. This was even if you had a thicker windhshield.

I opted not to go through with it due to the hassle.

Alfonso · #4 11-20-05, 09:20 PM

Thank you Ernie and Roger for your replies. I have contacted RT Aerospace as suggested by Ernie and we are making progress. I also contacted Cessna and there is also some progress. And thank you Ernie for guiding me to discover the 337SkymasterYahoogroup. However, I have had very much difficulty to access that board in spite that I followed all their instruction, changed passwords several times, but it runs me in circles. Can either of you help me out with it? One reply that was posted in that group gave me the idea that it was unsafe to remove the strap, and mentioned accidents that apparently happened, but when I asked for reference or accident number to look at it, apparently no number was available. So I downloaded the complete NTSB files of all 601 accidents and incidents reports since 1962 to the present "worldwide" on the Skymaster 336s and 337s and it is amazing what I found out so far. I have read about one half, and to my extreme surprise so far the main cause of accidents or incidents has been fuel exhaustion, mismanagement of fuel, and insufficient time on the aircraft. So far there is no one incident regarding the failure of the windshield or the windshield departing the aircraft. I am wondering if it will be a good thing to post on this board the complete "probable cause" of all the 601 cases in the NTSB record. Please let me know your thoughts. As a brand new owner of a Skymaster it really gave me a big lesson on how to handle better this C336. Thanks again for your help. Alfonso.

Ernie Martin · #5 11-20-05, 09:55 PM

I think, Alfonso, that there is some confusion here.

First, I never directed you to the 337Skymaster Yahoo group. I don't participate in it. Someone else might have directed you there.

Second, of course there has never been a windshield popping out of a Skymaster. The immense majority (probably 99.99%) have left the strap, so the aircraft remained structurally sound. A few might have removed the strap with RT Aero's STC kit , which reinforces the area so as to recover structural integrity. And I don't think anyone has been careless enough to do it without asking the kind of questions you asked -- and probably got the kind of answers you got: do it right (RT Aero) or don't do it.

Also, someone already posted the accident record with probable cause. Do a "Search" and you should find it.

Finally, because of the many fuel issues and their impact on safety, I have a whole section devoted to it in my "backup" site at www.SkymasterUS.com

Ernie