On Monday, December 4, 2017 at 8:00:06 AM UTC-6, Dave Nadler wrote:
On Monday, December 4, 2017 at 1:03:26 AM UTC-5, Darryl Ramm wrote:
...I have had no problem using McMaster Carr 3/16 (~5mm) bungee cord on
my ASH26E, and I've replaced engine bay door bungees several times...

Um, if you've had no problem, why do you need to keep replacing bungees???

I have replaced the gear door bungees on my gliders every few years, usually once they begin to get sucked open in a slip. I get about three years out of aviation bungees, and got one or two years out of commercial (Chinese) cord.
The seemingly short life I attribute to a very light installation preload, to minimize wear on the door surfaces, and constant stretched pressure. either with the doors closed or open. The correct tension therefore falls into a narrow range, which goes away within a few years.
I found it interesting that the aviation cords have a color code for the date of manufacture braided into the jacket.
cheers,
Scott, SHK & Std Cirrus