Hexagonal reinforcement patches on lower cowl?

[Joel Severinghaus]

I'm finally following up on some constructive nit-picking Larry Haas did on my plane at Oshkosh last summer. (It's actually quite an honor when the Taylorcraft nit-pickers can only find one or two nits to pick.)

Larry noted that my lower cowling (which was fabricated new in 2007) is missing the stainless steel reinforcement patches inside the curves at the lower rear corners. These are irregular hexagons, about five inches long and three inches wide, 0.025 stainless steel, each held in place with eight rivets.

Larry said he has eight old lower cowls, and they all have these reinforcement patches, but that I'd better do some research before using his drawings to add reinforcements to my cowl too.

Do all of your BC12-D lower cowls have these reinforcements?

[Mark Julicher]

Re: Hexagonal reinforcement patches on lower cowl?

Yep. All 4 of the planes I maintain have them.

When I rebuilt my lower cowl I made these doublers larger because the cowl tends to crack at the edge of the doublers. That won't be appropriate for a factory perfect restoration, but hey it works for every day flyers like mine.

[Hank Jarrett]

Re: Hexagonal reinforcement patches on lower cowl?

Every plane I have messed with (maybe 5 or 6) has had them, and like Mark said, most cowls had cracks. If they crack with the doubler, I would think they would rip like a newspaper in a high wind without them!
The other place mine have cracks is where the cabin heat support bracket connects to the cowl in the middle. That spot really needs a doubler.
Hank

[Joel Severinghaus]

Re: Hexagonal reinforcement patches on lower cowl?

Mark and Hank,

Thanks for the confirmation. Dave Wenglarz also phoned last night to say his original cowl has these doublers. But Dave said his are just zinc-chromated cold rolled steel, not stainless.

Larry Haas said his are stainless, but his serial numbers are 8738 and 10266. (By the way, Larry, bless his generous heart, also mailed me a little baggie of the hollow steel rivets used to attach these doublers to the cowling.)

Any idea whether my ship, serial number 8430, built in May 1946, would have had plain steel or stainless steel doublers?

[Ragwing nut]

Re: Hexagonal reinforcement patches on lower cowl?

I have only seen steel, zinc chromated. I even have a NOS short cowl from lock Haven plant and it is steel.

[Mark Julicher]

Re: Hexagonal reinforcement patches on lower cowl?

I agree with Ragwing Nut. Mine are all steel, not stainless. My BC12-D came out of the factory in Sept '46.

[Hank Jarrett]

Re: Hexagonal reinforcement patches on lower cowl?

Mine are painted (on both planes) so I don't know which material they are. It shouldn't really matter that much except that you want to really seal between them. You don't want bare SS in contact with aluminum. If I was putting either steel or SS doublers in I would fit them up, then bond them in with wet Polysulphide sealant and the rivets. That way you don't have a future problem with dissimilar metal corrosion (not that these doublers have been falling out of the sky).
Hank

[Joel Severinghaus]

Re: Hexagonal reinforcement patches on lower cowl?

I've said this before, but you guys are the best fringe benefit to owning a Taylorcraft. Thanks for all the prompt, precise advice.

Plain steel doublers it will be, zinc chromated, bonded then riveted per Hank's suggestion.

One less thing for Larry to nit-pick at Oshkosh this summer! Thanks!

[Robert Lees]

Re: Hexagonal reinforcement patches on lower cowl?

Mine were stainless (March 46 BC12D) as were the reinforcements on the upper hinged cowls and the reinforcements for the Dzus fasteners.

Because they were all riveted with those pesky steel rivets, I can only assume that they are original, especially since the lower cowl was butchered to fit the Brackett air filter.

Mine were all installed on a pre-painted surface, with "Pigeon Poo" Duralac as a sealant, and wet-riveted too.

[Robert Lees]

Re: Hexagonal reinforcement patches on lower cowl?

...The other place mine have cracks is where the cabin heat support bracket connects to the cowl in the middle. That spot really needs a doubler.
Hank

This is what I did. No cracks.

[Joel Severinghaus]

Re: Hexagonal reinforcement patches on lower cowl?

Thanks, Rob. As always, a photo from you is worth a thousand words.

[Joel Severinghaus]

Re: Hexagonal reinforcement patches on lower cowl?

Photos attached of my new stainless steel doublers on the lower cowling, owner-produced parts made according to Larry Haas' drawings. Thanks, Larry!

(No, didn't make them myself -- had some shop credit to use up at the FBO, so commissioned an A&P to do the work.)

Yet another detail to benefit the new owner of my plane...