What is that inside the green circle on the B717 MLG door please?





Regards

Ed

Looks like a rubbing strip so if the gear doors are not closed they will touch the runway and the strip will wear away rather than damage the doors.
It was like that on the BAC 1-11 and if the gear had been lowered by "Free Fall" the doors stayed open.
Same era and similar design. (DC-9 and BAC 1-11)

Thank you for your reply dixi118. What you said makes sense to me.

Regards

Ed

Was fitted to the Mad Dog. There to prevent damage to the doors when lowering gear on the emergency system. Amazing what you can remember from 30 years ago.

You are quite correct

Thank you guys for your help.

Regards

Ed

Later there was a mod to permit retraction. I recall one incident, alternate extension, door separated on touchdown, down the gullet, and a very expensive exercise overall ....

Can’t remember the name of the material that bumper is made of, but recall being instructed to avoid touching it on the exterior preflight due to skin toxicity. Guess rubber wasn’t good enough!

Nothing to add, but that’s a very clean airplane!

On the BAC 1-11 that was how you serviced the hydraulic reservoirs and brake system accumulators. I only worked on MD80s briefly so no idea if the architecture is the same.

Speaking of 717 tech issues, see the Twitter link in this article:

https://www.aerotime.aero/articles/v...7-leaking-fuel

Opposite for me. But yes, that's how the HYD system is serviced.

Reminds me of a day in MD-80 flght test when ferry tanks were being tested. I looked out the right window and saw fuel streaming from the wing tip. Stuck my head in the cockpit and said " Hey guys, do you know we are dumping fuel?" Was told - "We don't have fuel dump". I says "Go back and take a look". Turned out they had run the test card wrong and overfilled the wing tanks from the ferry tanks and the rest of it was going out via the vent box.

Wonder if this incident was similar with incorrect use of transfer pumps.

Closing the main gear door requires hydraulics. The Alt extension mechanically releases the main gear door and the gear which was supported by the door free falls and, hopefully, locks.

Why would alternate extension be used if there was hydraulic pressure available to close the door? A long time since I worked on MD-95 or MD-80 so may be forgetting some details.

It’s been a while, but from memory, after an alternate extension, you had to reset the alternate extension handle to get hydraulic pressure available to close the doors.

So much like the BAC 1-11. I wonder if the designers had lunch together?
With the 1-11's gear doors open there were locks to fit on the jacks to prevent them closing when you were working in the wheel well. I heard of one or two incidents when locks hadn't been fitted.

Some DC9s of the late 1960s vintage had a means to close the MLG doors following emergency extension (pretty sure I'm remembering this accurately but my DC9 manual is buried in the storage locker): There was a crank below the F/Os flight kit stowage area that when turned (about a zillion times) took up slack in cables attached by clips to the circumference of the MLG doors...and pulled the doors closed.

Thank you again for your knowledge guys.

I have another question. Do you know what the angle is that the reversers tilt inboard please?

15 degrees on the MD-80. Don't know if the same angle was used on B-717 which had different engines and nacelles. You have a good picture so it should be easy to measure.