Cowl hinge pin, rolled vs extruded.

[Freemasm]

Preceding thread is timely.

Many have experienced cracked eyelets with the rolled hinge sections. I’m playing with some extruded sections. It’s easy enough to get the halves to conform to the firewall shape.

Potential problem: What I’m feeling, = the extruded eyelets are much stiffer than the rolled ones for obvious reasons. Getting the hinge pin to thread through the shaped hinge halves (top along firewall) is noticeably harder to the point that I worry about getting them inserted with the cowl installed.

Please share your experience and remedies here if you would please.

Much thanks

 

[Dean Pichon]

In my -4, I broke a number of (rolled hinge) eyelets in both the top section (cowl to firewall) and both longitudinal sections (upper to lower cowl halves. I removed all the rolled hinge stock. I replaced the section between the firewall and upper cowl with Skybolt fasteners as installing the pins was always a challenge in that location, and, as you stated, I doubt they would go into an extruded hinge bent to that tight radius. I used extruded hinge to hold the upper and lower cowl pieces and have yet to break an eyelet (>10 years in service). I put a chisel point on the hinge pin and a bit of BoeLube along the length and they work great. I occasionally break a pin which can be challenging to remove so I replace the pins every couple of years to reduce the chance of breaking one.

 

[Roadjunkie1]

Preceding thread is timely.

What thread was that?

Many have experienced cracked eyelets with the rolled hinge sections. I’m playing with some extruded sections. It’s easy enough to get the halves to conform to the firewall shape.Potential problem: What I’m feeling, = the extruded eyelets are much stiffer than the rolled ones for obvious reasons. Getting the hinge pin to thread through the shaped hinge halves (top along firewall) is noticeably harder to the point that I worry about getting them inserted with the cowl installed.
Please share your experience and remedies here if you would please.

RV-4; rolled. I have not experienced any cracking or loss of eyelets. My pins are slightly smaller on the curved sections and original on the straight hinges. Makes them easier to put in and allows a slight flex of the cowling itself, reducing the load on the hinges. My pins have a point polished onto the ends and are pre-curved to match the curve of the cowling and hinge. 1200+ hours. I slick them up with a liquid slick-um (TriFlo or T6) on a rag and wiped clean to avoid any grease/oil on the cowling itself every time I put them back in.

 

[Richard RG]

I've got the extruded hinges installed on the 3b cowl and no problem inserting the hinge pins on the firewall and cowl halves. I keep the hinges clean and lubed and polished the retaining pins which have dull pointed ends. Two of the eyelets wore/cracked at the most forward end of the hinge and is where the tightest radius is on the upper/lower cowl half's. The airframe had just shy of a 1000 hrs when the two eyelets cracked.
The remedy to replace the cracked eyelets was cutting off the damaged eyelets flush with the hinge band riveted to the cowl and JB welding a replacement extruded eyelet segment to the hinge band. Flipping the new replacement eyelet segment opposite to the existing eyelets and slight bending achieved perfect alignment and no problems inserting the pin into repaired extruded hinges.