Accident Mildura

[facthunter]

The earlier Jabs had rather weak nose gear. They have been much improved. The undercarriages on most U/L's are not very strong. The requirement is not great.

 

Even most conventional light aircraft will damage a nosewheel in any event where it digs in at all but slow speed.

 

I like to have it removed before the plane is built.

 

Good questions Andy. I just read yout post.

 

You can only get an "opinion" from any of us.

 

A GA registered plane is not really permitted to be altered from the certified state without a lot of trouble and cost and time. This is why it's not done.

 

Regarding head temps.

 

It used to be possible to obtain paint which changes colour permanently above certain temps. A spray of this on certain external parts of the motor would enable you to know if that part had exceeded the desired temperature.

 

I have seen the inside of the cylinders with areas that have gone "blue" with heat on Jab engines. What temperatures do the piston crowns reach? Couldn't their temperature be as significant as the head temps in causing problems? Nev

 

 

[turboplanner]

It wasn't long ago that Jabs were fracturing main legs, and had to fit a suspension which would do justice to a light bulldozer.

 

If you land on the nosewheel, you're going to damage something, and I've seen a firewall buckled and a nose leg bent on GA aircraft on the smooth bitumen of Moorabbin.

 

Aircraft Spruce sell a ring thermocouple which takes the place of a spark plug gasket.

 

For the issues we've been discussing I would prefer to be looking at head temperature, and graphing it, to see what's going on inside the combustion chamber rather than downstream in the exhaust.

 

Exhaust gas can cool quickly, and its temperature changes at a different rate and time to the combustion chamber where the gas is compressed.

 

Nothing wrong with EGT for a general idea, but we are talking diagnosis here.

 

 

[jetjr]

Most EMS can produce logged temp data (if its turned on) - how much would you like to see?

 

Mine logs some 30 + parameters every few seconds have vast spreadsheets of information on a 3300 engine. Stores 5-6 hrs of flight before overwriting

 

Important to remember with any monitoring the absolute number you are getting is much less important than the changes, ie not if CHT is reading 120 or 180 but the fact that its 20 degrees above normal is the key

 

Im keen to find the temp stickers which black out sections as temp increases - used on large motor bearing housings etc

 

Ring thermocouples are an issue, thats what Dynon sell as Std, they dont fit the plug well and often cause gas leaks (that really screws with CHT readings), Jab now have small brass pin which fits into holes in head and thermo hot junction is crimped in.

 

My EGT vary greatly with very little impact on CHT, older thick finned heads were prone to overheating, new versions are a big improvement.

 

 

[turboplanner]

Ring thermocouples are an issue, thats what Dynon sell as Std, they dont fit the plug well and often cause gas leaks (that really screws with CHT readings), Jab now have small brass pin which fits into holes in head and thermo hot junction is crimped in.My EGT vary greatly with very little impact on CHT, older thick finned heads were prone to overheating, new versions are a big improvement.

I'm talking about the wrong measuring technology - I'd like to see the chamber temp which will be a lot more than 180.

 

The EGT is the one that will vary greatly in normal operations let alone when there is some ignition timing issue etc, that's why I tend to disregard it when searching for this issue.

 

 

[damkia]

I'm talking about the wrong measuring technology - I'd like to see the chamber temp which will be a lot more than 180.The EGT is the one that will vary greatly in normal operations let alone when there is some ignition timing issue etc, that's why I tend to disregard it when searching for this issue.

Replace one spark plug with a thermocouple on each cyl sequentially for some standing tests?

 

 

[Guest Andys@coffs]

Replace one spark plug with a thermocouple on each cyl sequentially for some standing tests?

Its a shame you cant buy a working spark plug with 2 inbuilt temp sensors, one at the thread for CHT and the other at the electrode. Placement and reliability of CHT and EGT sensors always gets a discussion, invariably people are unsatisfied with the current options.

 

Does such a thing exist?

 

Andy

 

 

[Garfly]

Jetjr, I've seen those stick-on temperature strips you were looking for advertised 'on special offer' on this site (Under "Jabiru Tech"):

 

http://www.xairireland.com/

 

But I suppose they're also available closer to home.