Check hose clamps

[rwarre]

Just did my condition inspection and noticed some oil dripping around the return tubes from the cylinder to the oil sump. All of the hose clamps were loose and some to the point of being able to move the hose by hand. Was told by an A/P that the clamps should be checked on a new engine and tightened.

[Walt]

Originally Posted by rwarre

Just did my condition inspection and noticed some oil dripping around the return tubes from the cylinder to the oil sump. All of the hose clamps were loose and some to the point of being able to move the hose by hand. Was told by an A/P that the clamps should be checked on a new engine and tightened.

On a new install/aircraft basically all nuts/bolts/clamps should be checked for torque at around 25 hours (first oil change). With the heat of expansion/contraction going on many critical item lose there tension. Exhaust studs are another important one to check.

When I do an annual on an RV, I put a wrench on EVERY critical nut/bolt/fitting on the airplane. I've never figured out a way to tell if something is loose by just looking at it.

[schristo@mac.com]

Originally Posted by Walt

I've never figured out a way to tell if something is loose by just looking at it.

Torque seal should be a reliable indicator...

[Captain Avgas]

Originally Posted by rwarre

Just did my condition inspection and noticed some oil dripping around the return tubes from the cylinder to the oil sump. All of the hose clamps were loose and some to the point of being able to move the hose by hand. Was told by an A/P that the clamps should be checked on a new engine and tightened.

You might like to consider safety wiring all critical hose clamps to prevent the screw threads from backing off.

[Walt]

Originally Posted by schristo@mac.com

Torque seal should be a reliable indicator...

I ignore torque seal when doing inspections, after things take a set they loose their clamping force, especially gaskets and rubber hoses, not to mention it may not have been correctly torqued in the first place.

I find plenty of stuff loose with torque seal on it.

[Lars]

Originally Posted by Captain Avgas

You might like to consider safety wiring all critical hose clamps to prevent the screw threads from backing off.

The problem isn't necessarily the clamps coming loose- depending on what they are made of, hoses will shrink a bit and extrude under the clamp. It doesn't take much before the clamp is loose. Not limited to aircraft. Auto hoses suffer from this as well- a common source of coolant leaks in my experience. I've started using only hose clamps that have a solid smooth surface in contact with the hose. It doesn't eliminate the problem, but it seems be be less.

[Walt]

Originally Posted by Captain Avgas

You might like to consider safety wiring all critical hose clamps to prevent the screw threads from backing off.

Does that prevent the rubber hoses from compressing and taking a set

I'd like to see anyone safety oil return hose clamps, you're a better man than me if you can

[Captain Avgas]

The advantages of safety-wiring hose clamps is obviously best determined on a case by case basis.

Here's a photo of a couple of hose clamps that have been safety wired on my heat muff. Click on the image if you want to enlarge it.

The screws in hose clamps are definitely prone to backing off in high vibration areas (particularly el cheapo hose clamps).

[Bavafa]

Originally Posted by Captain Avgas

You might like to consider safety wiring all critical hose clamps to prevent the screw threads from backing off.

During my airworthy inspection, the only dissatisfaction I heard from the inspector was the lack of saftey wire on hose clamp. He agreed, while he was finishing the paperwork and other things, I get busy with saftey wiring those clamps, so I did.

[N941WR]

Originally Posted by Walt

...
I'd like to see anyone safety oil return hose clamps, you're a better man than me if you can

Here's one way to safety those things. (Sorry, the picture quality isn't that great.)


(Click to enlarge)