Cowl Hinges

Chris Engler · #1 12-26-2014, 10:32 AM

Getting the cowls fit and using Skybolt fastners on the top and bottom cowls at the firewall. Was planning to use them on the horizontal seam as well but running into clearance issues between the Skybolt retainer and the rocker cover of the XP400 (it's wider than an IO 360). Based on the interference, I'll likely go back to a hinge fastner for the horizontal seam.

Looks like there are several choices for hinge material:

1. Rolled aluminum - MS20257P (supercedes AN257): The hinge Vans supplies with the kit and I currently have.

2. Extruded aluminum - MS20001P: Appears to be a more durable hinge from what I've read in other posts.

3. Rolled stainless steel - MS20257C: I would assume stronger and heavier than either aluminum hinge option but not sure if the strength/weight is necessary.

I'm leaning towards ordering the extruded aluminum (MS20001P)

Thoughts or suggestions are appreciated as always.

Thanks,

Chris

rvbuilder2002 · #2 12-26-2014, 11:49 AM

The longevity of any of the hinges is influenced by by much more than just the material choice.
Airframe vibration level (dynamic engine/prop. balance), cowl installed with preload/strain (force the cowl into a position that it doesn't want to be in during the fitting process), also have a lot of influance.
Having said that, the side hinges probably have the best longevity record on an RV. The 257-P3 hinge seems to works just fine. A lot of people using camlocks still use the hinge along the sides for a clean look.

David Paule · #3 12-26-2014, 11:57 AM

While not on an RV, my Cessna 180 had aluminum cowl flap hinges. Lots of vibration but not a lot of load. I'd guess that the load was the same order of magnitude as on an RV cowl hinge and the vibration worse.

The aluminum hinges didn't last more than about 2,500 hours. We replaced them with stainless and have had no more hinge problems. But the rivets that went from the hinge to the aluminum cowl flap work and I've had to repair those.

So I suppose the moral here is to make sure that the hinge fastener area of the cowl is robustly secure.

The extruded hinge might give a bit more protection against breaking the ears, since they have that second attachment of the ear to the flat part.

Dave

rvbuilder2002 · #4 12-26-2014, 12:05 PM

Hinge used for a component that needs to move (hinge) like a cowl flap, will endure a lot more vibration induced wear than the joint between the two cowl halves on an RV.
The RV oil filler door is a good example. The standard hing doesn't hold up very well over time. That is why a different hinging method was used on the RV-12, and now the RV-14.