The big door at the front of our hangar is maybe twenty feet high, forty feet wide, constructed of steel girders. I don't know how much it weighs, but it's got to be a ton or two.

There is a row of hinges along the top of the door. Each hinge is maybe ten or twelve inches long, and the row of hinges covers the full length of the door. Two hydraulic cylinder / piston things driven by electric pumps, one cylinder at each side of the door, open and close the door. To open, the door is pushed outward and up by the hydraulic cylinders; the hinges at the top carry the full weight of the door.

I'll post a photo in the next day or three, to show this.

Today, the hinge at the west end of the door broke, leaving that side of the door sagging a bit. I got the door closed and disconnected power to the hydraulic pump, as the door is unsafe to operate pending repair or replacement of the broken hinge.

This is the fourth time that the hinge in the same position has broken. Always the one on the west end of the door. I'm trying to understand the cause of the problem. Best theory I can come up with is maybe that hinge is not aligned properly, so that it is bearing much more than its share of the weight, and breaking due to stress.

Does anybody have any insight to this? Maybe a1abdj, who works with heavy doors?

This message has been edited. Last edited by: V-Tail,

A lifting device on a door that size seems way more prone to failure than a sliding door that is powered open and closed.

Does the design of the hangar prevent a simple sliding door?

I realize this does nothing for you problem Vtail, just what came to mind

Just a swag. Your thought that hinge alignment is one possibility to check. The other that comes to mind is from your description of the opening mechanism. If I read and comprehend correctly, the hydraulic cylinders on both sides of the door "lift" the door open. If the cylinder on the breaking side is doing more work (faster, different alignment, etc) it would stress the hinge.

quote:

Originally posted by OttoSig:
A lifting device on a door that size seems way more prone to failure than a sliding door that is powered open and closed.

Does the design of the hangar prevent a simple sliding door?

The Owners Association dictates the hangar appearance. All hangars have doors that are hinged along the top. Some are electric bi-fold, most are hydro-swing. No other types are allowed.

I have leased this hangar since July 2008. The owner had it built with the hydro-swing door; these are usually more trouble-free than the electric bi-fold, but this door has failed the same way, multiple times.

I am not there every day. I'll post some photos within a few days.

quote:

Originally posted by SPWAMike0317:

Just a swag. Your thought that hinge alignment is one possibility to check. The other that comes to mind is from your description of the opening mechanism. If I read and comprehend correctly, the hydraulic cylinders on both sides of the door "lift" the door open. If the cylinder on the breaking side is doing more work (faster, different alignment, etc) it would stress the hinge.

I do not know that much about hydraulic systems, but I was under the impression that with a single pump driving both cylinders from a common manifold, the two cylinders would be operating with the same pressure. As far as condition, there had been some hydraulic leaks, so both cylinders were rebuilt and all hoses and fittings replaced the last time that the door failed.

You are correct about operating pressure.
However, internal leak of the actuator can result in unequal force applied.

Given they have been changed, unlikely they are the cause. Unless the mount point is off on one side applying unequal force.

But I think you are correct that the hinges is being side loaded from bad alignment.

Do the hinges have floating adjustment or "drop fit" and "pinned" by the fasteners.

And may need to look at the hinge for "depth" (too far in or out of the opening) as well as side to side and up an down for that one hinge.

Since this is an on going problem and only on one side, two things come to mind. One, is the hinge pin on the problematic hinge parallel to the other hinge pins.

If so, I’d look at the geometry of the rams. As in taking measurements of the three pivot points on the one side of the door and comparing the measurements with the three pivot points on the other side of the door. I’d check the measurements at various door opening postitions.

The three points should be:
Ram to door
Ram to jamb
Hinge

The two measurements from the hinge should be fixed and equal on both sides no matter the position of the door. Obviously, the distance between the ram points varies based on the opening of the door, but should be equal on each side. In other words, the length of the rams should be equal to each other when the door is closed, open halfway, fully open, or at any opening in between.

As has been noted already, this is a recurring problem. The hinge being broken more than once would point to an alignment problem.

I think you might be better to have the door taken down, all checked on the ground for being straight (hinges in the folding portion might be part of the issue), then installing it as if a new door so that measurements can be done without load to help remove doubt as to any problems in the future.

Another solution might be to ask to move to another hangar.

quote:

Originally posted by V-Tail:
I do not know that much about hydraulic systems, but I was under the impression that with a single pump driving both cylinders from a common manifold, the two cylinders would be operating with the same pressure. As far as condition, there had been some hydraulic leaks, so both cylinders were rebuilt and all hoses and fittings replaced the last time that the door failed.

It's a one piece door, so there aren't any hinges horizontally in the middle of the door. The entire top of the door is attached frame all the way across almost like a piano hinge. The force to open the door is provided by two hydraulic cylinders; one mounted on each side of the door. Upper end of each cylinder is mounted to the door frame above and behind the bottom end which is mounted to the door. The ends can't be plumb or the door won't open. A couple people at the airpark my parents used to live in had this setup. My parents had the bifold setup.

The hinges all the acrosss are interesting. If there where only one hinge on each corner, the middle of the 40' door would sag more and more as the door was opened unless you used a truss like the bottom edge of the door. There's a lot of interesting engineering that goes into those doors.

To help us diagnose the issue, could you share the nature of the “broke?”

Of the three hinge elements, the pin, the frame anchor, or the door plate, which broke?

Could you estimate the number of opening and closing cycles between failures?

Are the end hinges the same exact hinge as the rest of them?

Do the hinges receive any periodic lubrication between the pins and the mating “holes?”. Absent a great grease, the torque on the hinge elements could result in momentary extreme pressure “scuffing” failures leading to a fracture.

If you have seen the broken hinges before, could you describe the breakage surfaces as either “smooth” or “rough?” These surfaces help identify the type of metal failure (fatigue or overload), and potentially the material choice of the pin or element.

If you have seen the broken hinge elements, do you see any signs of twisting, torsion, bending, etc.?

Regarding alignment as a potential cause, since this failure has occurred before, any misalignment would necessarily be of the door frame or the door itself. Another reason to change hangars?

Regarding hydraulics as a potential cause, a differential actuator speed could cause a different torsional condition on the hinges, from side to side. Imagine your shower door. Often grabbing it at the top, or pushing it open at the top will result in a skew of the door. Is this massive door twisted? Or, has it, with its girder construction, maintained its planar shape? Are the hydraulic lines of equal length, diameter, bending, etc.? Is either line constricted to prevent an actuator from receiving the same fluid volume?

When the hinge is replaced, does this occur easily? Or, do they beat the thing into submission with a nine-pound hammer? The latter would suggest misalignment.

Did any ground vehicles impact the massive door, causing it to twist?

quote:

Originally posted by SigSAC:

Another solution might be to ask to move to another hangar.

The hangars are privately owned. I have leased this hangar -- the whole 3,500 sq. ft. hangar, including office space upstairs and downstairs, storage loft, tiny kitchenette and bathroom with shower -- from the owner (a senior SouthWest captain) since July 2008.

Hangar space is at a premium at Our Little Airport.

A picture or two would be helpful. As you describe your door it is both bigger and different than mine, though my door is 48' wide, but only 10' tall. Mine has a short track on each side that the door cams up and in on top, kicking the bottom of the door out. There are some pretty heavy duty forces on the wheel and track on mine.

I agree with others as to unbalanced forces side to side contributing to or causing the failure

We are still investigating the cause, but we have some information that might shed some light on the cause of the failure. We have been in touch with the company that services these doors. Might know more later this week.