Loose prop on Bantam B22J / Jabiru 3300

[tigger_na]

Dear Forumites

During a pre-flight today we found that the prop was loose on the prop flange, and had been loose for a while already. The locating studs developed a groove where they go through the flange, the holes in the flange are now slightly oval, the prop mounting bolts are worn thinner and the prop has a few minor cracks radiating outwards from the mounting holes. The bolt torque was checked four hours ago, in accordance with the manual.

What could have caused this? I maintain that to check a torque you must first loosen the bolt and then re-tighten, otherwise you're working against static friction and this gives a higher torque reading than when the nut is torqued from loose.

Blue skies
Arthur

[pit bull]

dag Arthur,

ek het jou n mail gestuur.

pit bull

[lefssa]

Have you complied with Jabiru recommendations to fit the longer bolts with 9 washers on the bolts. this seems to fix the problem of the nuts coming loose. I also had this problem but it has not happened since i did the mod.

[tigger_na]

No, I haven't. Will follow up, thanks for the tip!

This is Jabiru Service Bulletin JSB022? (http://www.jabiru.net.au/Service%20Bull ... nting).PDF) I'm not at the aircraft, but I think it's impossible to fit the bolt through the prop flange with the tread pointing forward, there's no space between the flange and the engine block to get the bo..., Wait, If one inserts the bolt in the guide bush first, before fitting the guide bush, this should work.