Preflight Inspections - look harder!

[Jabiru7252]

The aircraft, an FK9 was flown at least once with this bolt broken. The bolt was NOT hanging down as shown in the photo, it was in place so the defect would be hard to spot. Makes one wonder just how meticulous one should be doing the daily inspection or preflight. The bolt is on the pilot side forward of the undercarriage. In my opinion, heavy braking may have caused the bolt to give, but, what would I know? Hope this post is of use....

 

 

 

[ayavner]

wow, shocking! could have been a bad crosswind landing with a too-heavy side load? I always try to check for excessive play in the undercarriage, wonder if my usual check would have found this or not? hmmmmmm

 

 

[cheyenne]

The standed check on the Jabiru under carrage bolts is to grab the strut and push the leg forward with your foot any movement detected, then check the bolts.

[Yenn]

The object of the check is to find a reason not to fly. If you can't find one then it should be safe, but it depends upon how hard you look, then again it is too easy to miss something. I have a piece of 1/8" pipe goes into my pitot tube to stop the bugs building. Forgot to remove it yesterday, but the tiny hole in the middle gave me a reading, but I think it was a bit low.

 

 

[Methusala]

At least 1,000,000 ways that an aircraft could kill you. Watch out! Don

 

 

[facthunter]

U/C retaining bolts near to fracture would be hard to detect. If this is a common fault remove and inspect/replace at a set interval. Dependent on where you use the plane. Any hard landing should be subject to an inspection It's more likely this resulted from a series of loads rather than one. It it was just one it should have failed The thread itself is a crack start point in many situations. Nev

 

 

[Jabiru7252]

The standed check on the Jabiru under carrage bolts is to grab the strut and push the leg forward with your foot any movement detected, then check the bolts.

Yes, I give my plane a good wobble about with brakes on and watch carefully for any movement. This plane, an FK9, not a Jabiru is very similar to the Jab with respect to the under carriage so the same check could apply. This bolt has snapped off flush so the remaining bit might be fun removing. I might sit back with a beer or coffee and watch with interest the job undertaken.

 

 

[Compulsion]

The job was done yesterday. A real bitch for Mick. Stuck solid and took a lot of hard work. Last time I walked past the hangar Mick was still trying.

 

 

[Downunder]

Drill and eazy-out?

 

 

[bexrbetter]

You should do what us race car blokes do, grab a handful of spanners and go run them over every nut and bolt you can see, it only takes a few minutes and it's surprising how many look sound but are just sitting there, just waiting ....

 

 

[motzartmerv]

• Not familiar with the FK9, but the jab service schedule is to replace the bolts at every 500 hours ( I believe). So its probably not a bad idea for other types of similar U/C design. With this design, and the sprung undercarriage, the normal failure point for a heavy landing is not the bolts, but the monocock somewhere else, ie the wall of the fuse etc. The bolts and u/c are normally found to be ok.
   
   
  

 

 

 

 

[frank marriott]

Just did the 500hr replacement - interestingly 2 bolts had a slight bend - I can't blame anyone for a heavy landing as I am the only one who has flown it, I don't recall anything significant in the landings but nobody else to blame.

 

 

[motzartmerv]

Frank, I doubt you would have bent them with a heavy landing. We just did ours a few months back, and our training j230 copps a pretty hard time, and its bolts were not bent. Was it the first round of replacement for you? I know they changed the bolt types a few years back.

 

 

[frank marriott]

Frank, I doubt you would have bent them with a heavy landing. We just did ours a few months back, and our training j230 copps a pretty hard time, and its bolts were not bent. Was it the first round of replacement for you? I know they changed the bolt types a few years back.

Yes, just clocked up 500hrs - they were not bad, cracked or anything visible but obvious had some stress load at some time. 2008 model. I would have thought in the training mode they would have a good workout at times.

 

 

[motzartmerv]

Yes Frank, we are pretty rough on them..:) They have always stood up to it. The airframes are absolutely brilliant, and tough. The one heavy landing causing damage we have had cracked the 'shell' behind the door. Not much but enough to require repairs. The U/c flattened out that much there was grass stains on the belly. But no damage to the u/c legs themselves.

 

 

[Guest Pioneer200]

bloody hell,grass on the belly? MOTZ was it flared at 10,000 ft LOL

 

 

[motzartmerv]

Nope, it had a partial engine failure at about windsock height. The pilot pulled the throttle and she flopped on pretty heavily. The engine had 49 hours on it:) The engine was returned to factory (with the rest of the aeroplane) and the reason given for the failiure was incorrect spark plug gapping:)..Yep, you read that right...

 

 

[rankamateur]

Were there any stains on the inside of the fuselage?

 

 

[biggles5128]

Nope, it had a partial engine failure at about windsock height. The pilot pulled the throttle and she flopped on pretty heavily. The engine had 49 hours on it:) The engine was returned to factory (with the rest of the aeroplane) and the reason given for the failiure was incorrect spark plug gapping:)..Yep, you read that right...

Too wide a gap or too narrow Motz, did they say ????? I have just closed the gap on mine to help with the cold starts in the minus 10-15 part of the country where I live. So would be interested to hear their theory on that.

 

 

[motzartmerv]

They said it was too wide I think (was a few years ago). No person with any sence would entertain the idea that a gapped plug could cause a sudden partial engine failure out of the blue.

 

 

[Old Koreelah]

U/C retaining bolts near to fracture would be hard to detect. If this is a common fault remove and inspect/replace at a set interval. Dependent on where you use the plane. Any hard landing should be subject to an inspection It's more likely this resulted from a series of loads rather than one. It it was just one it should have failed The thread itself is a crack start point in many situations. Nev

Whatever happened to "bleeding bolts"? Seemed the ideal solution the problem of invisible cracks,

 

 

[AVOCET]

I've found on the jaby type U/C that grass or rough ish dirt strips really vibrates the U/C ,on the avocet you get a good view of the wheel & leg and i was suprised how violent it moves back & forth ,even on the taxi , it looks like the bolts are loose . I would think this has a fatigue effect on the bolts , as I have replaced several over the years with slight bends .

 

It used to be the back bolt on the old Jabys

 

Doesn't seem to be as much of an issue if they are only used on the Tarmac .

 

Cheers Mike

 

 

[Old Koreelah]

I've found on the jaby type U/C that grass or rough ish dirt strips really vibrates the U/C ,on the avocet you get a good view of the wheel & leg and i was suprised how violent it moves back & forth ,even on the taxi , it looks like the bolts are loose . I would think this has a fatigue effect on the bolts , as I have replaced several over the years with slight bends . It used to be the back bolt on the old Jabys

Doesn't seem to be as much of an issue if they are only used on the Tarmac .

 

Cheers Mike

You're right about the Jab UC getting taking a caning, Mike. While landing on a rough grass strip the inner RH leg bolt suddenly failed. Old mate instructor beside me was unfazed as we skidded to a stop, dragging the R wingtip across the tussocks. Good design: prop didn't touch the ground, and I was able put a seat cushion on my head, the wing on top of that, as the bolt was replaced. Then back in the air!

 

 

[nomadpete]

 

Preflight? Just a quick walk around should do...

 

Anyway, you can always check it later.....

 

 

[biggles5128]

They said it was too wide I think (was a few years ago). No person with any sence would entertain the idea that a gapped plug could cause a sudden partial engine failure out of the blue.

A wide gap will place more load on the electrical system i.e a greater electrical potential so it would be possible in theory to have a rough running engine while under load.. As electricity will take the path of least resistance and may very well try to track across a bit of carbon around the plug. Thats the way I understand it anyway.