Niggly maintenance observations

[old man emu]

Since I'm involved in maintaining a couple of Jabirus that are on line at a flying school, I might see little niggly things to do with maintenance. They are simple things that may be overlook in the hurley-burley of this type of use. If you use a Jab from a flying school, you might like to look out for these things.

 

1. Oil.

 

The sump doesn't hold much. I had to get a longer dipstick to find out how much oil was in one just before it set off on a 3 hr Nav. It took about 800ml to get the level back to full.

 

2. Door hinges.

 

Don't let the wind catch the doors and fling them open. It cracks the hinges. Don't leave doors open and unattended on the ground in case of wind gusts.

 

3. Report missing lock screws from around the top cowl, and loose or missing screws from the lower cowl.

 

I'm sure to have more to report as time goes by.

 

Old Man Emu

 

 

[Guest Ken deVos]

Brake lever ratchet

 

Is there a good fix for the annoying habit of the brake ratchet running out of teeth, rotating past the last segment and then falling through the opening?

 

I imagine this problem is caused by progressive brake pad wear and the ratchet simply runs out of travel to compensate.

 

Recently, when parking at a windy ALA, I needed to roll up my weather briefing sheet and jam it in the slot so the ratchet had something to grip.

 

 

[Wilfred]

The brake is not really a parking brake.

 

We use a couple of light pine chocks when parking the aircraft. These are left in the aircraft

 

Since then the brakes don't seem to need adjustment & bleeding as often.

 

Also made a oil dip stick that is kept in the hanger to give an accurate oil level. This was calibrated with marks as the sump was filled to ensure it is pretty accurate.

 

The oil takes a long time to run down and give an accurate level reading so its best to add the right amount first up.

 

Definitely have the same problem with the doors although i imagine this is a problem with many aircraft.

 

 

[old man emu]

Is there a good fix for the annoying habit of the brake ratchet running out of teeth, rotating past the last segment and then falling through the opening?

Have you tried applying the foot brakes firmly, then pulling the hand brake lever until it is firm?

 

I'd only use that method of applying the brakes for short stops, like while getting fuel, or doing a pre-takeoff run up. If you are going to leave the aircraft parked and unattended, I'd got for wheel chocks and leave the brakes off. You won't be holding pressure in the system, and you a/c can be pushed around if an emeregency arises and you aen't there.

 

You can get cheap metal folding wheel chocks at discount car parts shops.

 

Old Man Emu

 

 

[Guest Ken deVos]

Have you tried applying the foot brakes firmly, then pulling the hand brake lever until it is firm?

Hi OME, not exactly sure where the foot brake is in the Jab :big_grin:

 

Perhaps the equivalent to your remedy is to pump the brake lever a number of times before engaging the ratchet mechanism.

 

Annoying though, if you have to pump the brake lever after finding that the ratchet has run out of teeth, then having to use both hands retrieving the ratchet while holding the brake on with engine running.

 

I fully agree with both you and Turtle regarding the use of wheel chocks.

 

 

[old man emu]

My bad. I'll have to stick my head in the footwell to see if the Jab has toe-brakes. I haven't been working on them long, and haven't needed to work on the brakes.

 

Old Man Emu

 

 

[Guest brentc]

After hundreds of hours in the Jab I can tell you that if the handbrake ratchet is not ratcheting (don't know if that's actually a word), then the brakes need adjusting. It doesn't take more than a minute or two to tweak up the brake calipers every 10-20 hours or so. The problem is that if you don't tweak up the calipers and the pads have worn, the piston can come out too far from the housing, cock sideways and the fluid will leak out and you will have no brakes whatsoever, a very dangerous situation. Another idea Ken might be to apply the handbrake after switching the engine off so as to avoid the requirement for 2 sets of hands.

 

One thing that annoys me about many Jabs is the high idle that people set them at. 800 rpm on the ground is more like 1,000 in the air. If you're on final and trying to slow down and land it short you will be pulled along by the engine which will frustrate you and circumvent your short-field technique. I set my idle to as low as it can go without stalling for ground use, then in the air when I throttle back on final, it won't go below 800rpm. The bonus of this is a much slower approach with a shorter landing.

 

OME, oil consumption is not usually an issue, however if the aircraft required 800mls to get it back to the mark again, I would suggest taking to the pilot that last flew it. You need not fill the oil level past the bottom mark, otherwise the excess will blow out. This is a documented Jabiru fix on their website for blow-by problems.

 

 

[Guest Ken deVos]

Another idea Ken might be to apply the handbrake after switching the engine off so as to avoid the requirement for 2 sets of hands.

This problem usually catches me after taxiing to the run-up area where three hands are often required.

 

 

[Yenn]

Iv'e got my Jab 2.2 idling on the ground at about 800rpm and the prop drives the engine in the approach, but it isn't increasing air speed in fact just the opposite. Occasionally I get an engine stoppage landing when the nose is right up and very little speed, it doesn't happen often. I have to use a longer dipstick with the angle in a taildragger and it pays never to fill it right up.

 

Ian Borg

 

 

[theoy]

Hi Ian next time just after you have landed, have a look on the bottom outside of the carby see if it is wet. It might be flooding. It could be the needle & seat , carby floats or electric boost pump . I had a similar problem with my Jabiru 2.2L.

 

Cheers

 

Theo

 

 

[BigPete]

My Brake Mod

 

This is how I solved the problem of the missing ratchet. Just a small strip of aluminium screwed to the top of the ratchet.

 

regards

 

 

 

 

[old man emu]

Marking your pitot and static plumbing

 

While investigating a problem with an airspeed indicator and altimeter which were not operating properly, we had cause to check the plumbing between the pitot tube and the junction at the starboard wing strut root.

 

Hmmm ... both pipes looked exactly the same and went into connectors which looked the same as each other. This was a actory built plane. Which was which? Well, after we had disconnected the lines and did some sucking and blowing, we found out.

 

HINT 1: Wrap a piece of masking tape around each pipe and write "pitot" or "static" as appropriate on the tape on each pipe. Do the same for the pipes leaving the connector and going to the instruments.

 

HINT 2: If you are going to check for blockages in the pitot system plumbing by blowing from your lungs, don't blow like you're blowing up party balloons ;) , and definately don't use air from a compressor.

 

A very slight puff is sufficient to move the needle on an ASI or altimeter. If you need to maintain continuous pressure, just take a deep breath; put your mouth over the pitot head and contract your diaphragm.

 

Old Man Emu

 

 

[old man emu]

A screw loose

 

I've been helping to service another Jabiru and found the following:

 

1. Head bolts required re-torquing.

 

2. The nuts holding the alternator in place were loose about a quarter turn.

 

3. The HT leads at the magnetos were loose.

 

This in an aircraft with about 300 hours' time. It's a flying school aircraft, so the hours are racked up quickly.

 

If you are maintaining your own aircraft, it would pay to wave a torque wrench around in the engine bay about every 25 to 33 hours.

 

Old Man Emu

 

 

[Guest osprey5]

Turtle - have you got the dimensions and markings of your oil stick. I find it a real pain having to guess the amount of oil and wait 5 mins before taking another reading. I check the oil first and then do the pre-flt inspection which gives the oil time to drain down ready for another reading and another top up. Sounds like you've come up with a great idea of a calibrated dip stick...

 

 

[Wilfred]

We sat back one rainy day when we were doing a service and used a bit of braising rod that reached to the bottom of the sump . glued a cool knob to the top so it sticks out like the proverbial and doesent get lost, then put marks on it as we added oil ,one litre at a time ,with a bundy break to let it settle.

 

It is accurate and we also try to make sure if leaving from the hanger to check it with the aircraft in the same spot each time.

 

 

[Guest J430]

Turtle system seems to work, however for those with out a Turtle stick, I would suggest you dip several times and compare, some times the oil level is there but has wicked up the side of the stick giving a higher reading!

 

Screwing the cap down wobbles the stick around in the tube (its not concentric) and you get the stick touching the sides of the tube. You can just use the stick to dip and retrieve and then by measurement allow for the thread length not wound in! Works ok for me.

 

J:)

 

 

[old man emu]

Broken door hinges

 

Check the length of the fabric strap which sets the limit on how wide the doors of your aircraft will swing open. I've just pulled the door off an aircraft that has had its door hinges come loose within the door assembly.

 

Don't know yet if the hinges can be re-attached to the door, or if the owner is up for a new door.

 

Old Man Emu

 

 

[Guest brentc]

Door hinges are usually just fibreglassed on. You'll need to get some Arildyte LC3600 resin and hardner (3 parts to 1 part hardener) from Jabiru. If it's an older model, they will have used a combination of fibreflock and rivets. Either way, pretty easy to repair, but not necessarily a very cosmetic repair.