Jab altimeter

[Jabiru Phil]

Hi all,

 

I found that my Altimeter has been tampered with. It now reads around 3500 ft at my airfield (125 ft)

 

Seems that someone possibly a child has wound the knob passed the stop. Not at this airfield.

 

I guess that the only way to calibrate again is to take the readings from another plane and set the alt with the QNH

 

Is this my best method? as very costly to send away and they may not inspect due to not being an approved brand.

 

I did set the taf QNH and airport height the other day but yeaterday it was about 70 ft out using QNH again.

 

Regards,

 

Phil.

 

 

[facthunter]

Altimeter test.

 

If you are somewhere with a tower who can give you an accurate QNH and you know the Height of the drome, your method is the normal way of doing it. You have an allowable error, which I can't recall but I don't think you are far out. Using the Forecast area QNH is not up to the job, ( but it's a good start) On the figures you quote the Altimeter may still be OK. Compare with somebody who has a correct reading alt and have your kollsman scale set the same ...Nev

 

 

[RKW]

Hello Phil, It may be that your altimeter has simply packed it in. I have had two go on us in my J160 and another in the J170. Sounds like the same symptoms that you described. They are not a high quality item and I don't believe they are worth repairing. We seem to be accumulating them as ornaments at the flying school! Best Regards, Bob

 

 

[Jabiru Phil]

THANKS FOR THE COMMENTS.

 

I will use the EFIS and GPS until I can be satisfield that is is behaving correctly.

 

If not, spend $$$

 

Regards.

 

 

[billwoodmason]

I think RKW has hit the nail on the head. I've had a similar experience with the Alt in my LSA jab a couple of years back. Did a lot of fiddling - thought I had it right, but it kept going haywire. Bought another one - problem solved.

 

Cheers,

 

Billwoodmason

 

 

[facthunter]

GPS height.

 

Beware. GPS derived height will not be the same as the one derived from a calibrated and baro referenced altimeter. You will not have the required separation from other airspace users. Nev

 

 

[Jabiru Phil]

Thanks Nev, good point.

 

I only intend to check Baro with calibratd EFIS and only curcuit and local flying until I get it sorted,

 

Phil.

 

 

[jeffcb52]

Hi all,I found that my Altimeter has been tampered with. It now reads around 3500 ft at my airfield (125 ft)

Seems that someone possibly a child has wound the knob passed the stop. Not at this airfield.

 

I guess that the only way to calibrate again is to take the readings from another plane and set the alt with the QNH

 

Is this my best method? as very costly to send away and they may not inspect due to not being an approved brand.

 

I did set the taf QNH and airport height the other day but yeaterday it was about 70 ft out using QNH again.

 

Regards,

 

Phil.

I have had three of those useless chinese altimeters. The last on did 5 hours.

 

 

[mlpinaus]

Yes, the one on my 230c lasted about 100 hrs. Died at a permanent 3500 ft..... must be something they do. Not cheap either for Chinese rubbish. Waiting for the new one on my 230D to fail.

 

Marcus

 

 

[ahlocks]

The original one in the Czech rivet box met with the same fate. Had to continually recalibrate the Kollsman scale and I didn't trust it for anything more than a local flight, so replaced it. Heard two different yarns as to why they do it.

 

1. A set screw slips internally - supposed to repairable for around $50

 

2. A fusion weld lets go on one of the aneroid chambers - chuck it away and get a new one. ~$300 and a couple of hours to R&R

 

I probably should pull the old one to bits and see what actually did go kaput....

 

 

[cheyenne]

I have replaced 2 Altimeters in my J160. Gave up on the units from Jabiru, as the bellows crack. Spent the dollars and fitted a Falcon Altimeter.

 

 

[dazza 38]

I would like to here from Andy from Coffs Harbour on this.He is a ex RAAF instrument fitter and still applies his trade with BAE systems at Willy town.He also owns a Jabiru. He realy knows what he is talking about. This thread is interesting, im not trying to open a can of worms, but there seams to be a problem with some of the instruments fitted to some of the jabbys.This is realy interesting.

 

 

[ahlocks]

It's not just Jabbys Daz. It's a matter of quality control lotto with most China made stuff.

 

 

[Ultralights]

to calibrate it, take your aircraft to the nearest aerodrome reference point, its will be the same height of the aerodrome published in ERSA.

 

 

[dazza 38]

It's not just Jabbys Daz. It's a matter of quality control lotto with most China made stuff.

So true, Steve.I guess thats modern society.Everything is built to a price.It depends on what people are prepared to pay.

 

 

[Dieselten]

Aviation Salvage in Taren Point, Sydney, were able to supply me a very nice sensitive altimeter, formerly fitted to a Cessna, TSO'd and checked, when my factory-built J160 suffered a sticking altimeter. When in doubt, throw it out and get a decent, refurbished TSO'd unit from a reputable supplier. Ultimately it will cost less than replacing Chinese instruments with still more Chinese instruments.

 

 

[jakej]

Good advice, Dieselten. I will not buy any of the Chinese instruments for my customers, just not worth the grief with the lack of reliability - I know of one of the altimeters being declared u/s straight out of the box (out of warranty due sitting on shelf while the plane was being built). Wultrad or Falcon, makes no difference - maybe in time they will get better just like the Jap stuff decades ago.

 

I wonder how many of these are in certified aircraft and attempts made at repair ? Most decent 'shops' won't try to repair them as there is no repair/maintenance manual so, then by default, you cannot repair these units and issue a cert under FAA 43 appen F.

 

Maybe a poll should be done to ascertain how many have/or are having problems with these units - I'd suggest a lot. AS I see it the only reason they are fitted is because of the price.

 

 

[Guest Andys@coffs]

The altimeters supplied by jabiru are indeed rubbish. I especially cringe when I see them in an aircraft that has a transponder fitted as its the same pressure line that also connects to the (usually) AmeriKing AM-350 altitude encoder. I'm pretty sure that to use the transponder (at least in Mode C)requires that the instruments that are attached to it to be TSO'd and regularly calibrated.

 

Changing a dud altimeter for another, where it involves disturbing the pressure line (....Duh, thats every change!) , means that a new claibration is immediately needed. (And I bring this up because in addition to being a crappy chinese instrument my nylon pressure line T piece was cross threaded on the instrument in the J230 when it failed, so all pressure instruments hanging off the pitot line would have been wrong because the line was open to atmosphere in the cockpit)

 

My experience with the chinese instruments is very poor, Ive had 2 of these altimeters fail (supplied in my Airborne trike and my J230) and a cheap (only in value...not in cost!!) electric AH fail (It too was branded Falcon...Dodo seems more apt!) in each case I refused to repair and refit it for the reasons Jake identified a) No documented and repeatable repair methods, and b) I didnt have the set of kitchen knives, nailfiles and sledge hammer needed to manufacture a replacment part from the required fencing wire and bald tyre.

 

The AH was replaced,with a fully electronic (No moving parts) solution that because its electonic and has a cpu also provided DG capability as well. No good for anything other than VFR as not certified, but met my need to have no empty holes in the dash :<) . There are fully electronic approaches to Altimeters as well, but I havent checked to see if there is a certified solution at a cost thats appropriate to the segement of aviation where we sit.

 

Andy

 

 

[old man emu]

Today a customer came in with an altimeter problem in his Jab. The problem was that the sub-scale had slipped. The altimeter was a factory fitted Chinese one.

 

We had experienced this problem previously in another airplane, so we decided to investigate the options. These were:

 

1. Send the instrument to the instrument maker for repairs and checking.

 

2. Buy a ready-to-fit 2nd hand, Made in USA one, with certificate, from a local parts shop.

 

3. Buy a 2nd hand, Made in USA one from an aircraft dismantler, then send it to the instrument maker for calibration.

 

4. Buy a Chinese one "new in box" from Jabiru.

 

The quotes we got were:

 

1. $209 and "checked only"

 

2. $580 + GST, certified calibrated

 

3. $380 + GST for the altimeter, then $209 for certified calibration.

 

4. $290.90 + GST and hope it's a good one.

 

When I spoke to the instrument maker, he told me that his certification for a Made in USA would be acceptable as an Instrument 8/9 inspection for a VH registered plane. However, he could only say that the Chinese made altimeter was "checked" because the required data necessary to repair and calibrate Chinese altimeters did not exist. There are no Service Manuals or Specifications for them. His repairs were based on his many years' experience as an instrument maker.

 

If the instrument maker can't fix the problem with the slipped sub-scale, the owner is going to be up for another altimeter. He can buy a Chinese one; save $260, and hope he has no further problems. If it does play up, he's going to have to get it fixed at $209 for a total outlay of $529, which saves him $50 on the first breakdown. And there are no guarantees if the instrument fails again.

 

The choice is the owner's, but this might proved to be a case of "Penny wise, Pound foolish".

 

Old Man Emu

 

PS:

 

The instrument fitter thinks he can repair the problem by giving the wave spring behind the faceplate a bit more tension. But he's not promising anything.

 

 

[old man emu]

Free to a good home .... One Chinese manufactured altimeter. Would make an interesting paper weight, or could be converted into a desk clock.

 

I picked up the offending altimeter from the instrument man today. He said that he didn't even try to fix the slipping sub-scale because he noticed that the temperature compensator was not working. He said that he had left my altimeter on the bench overnight beside another altimeter, pending starting work on it the next day. When he came back the next morning he noticed that my altimeter was showing about 100 ft difference from the other one. He reset mine and put both outside in the sun. In about half an hour, mine was reading differently from the other.

 

Not having access to any technical information about the particular altimeter, and there being no spare parts available in any case, he told me that it was not worth going any further with it, and handed it back.

 

We spoke to the owner of the aircraft who approved the purchase of a 2nd hand altimeter for $500 + GST. He'll be back in the air early tomorrow.

 

OME

 

 

[long tall texan]

Looking at new altimeters. Can anyone tell me please the difference between" sensitive" and "insensitive" and what type do we normally use or more frequently used?

 

 

[old man emu]

A 'sensitive' altimeter has two or more indicator needles and can read to very great altitudes. An 'insensitive' altimeter has only one indicator needle and usually only reads up to 10,000ft.

 

The usual altimeter that you see around the place is the 'sensitive' altimeter. You probably will never see an 'insensitive' altimeter unless you are looking at a museum exhibit or a very vintage plane. Insensitive altimeters are very rare in Australia.

 

Old Man Emu

 

 

[jakej]

A 'sensitive' altimeter has two or more indicator needles and can read to very great altitudes. An 'insensitive' altimeter has only one indicator needle and usually only reads up to 10,000ft.The usual altimeter that you see around the place is the 'sensitive' altimeter. You probably will never see an 'insensitive' altimeter unless you are looking at a museum exhibit or a very vintage plane. Insensitive altimeters are very rare in Australia.

 

Old Man Emu

Actually .... some people have been using the single pointer (one needle) type, they are useless in terms of 'approval' and compliance with FAR 43 appen F .

 

Jake J

 

 

[old man emu]

Just to ad a bit to this conversation.

 

You can still buy insensitive altimeters and they are about $300 less than sensitive ones. However what you must consider is the readability of the instrument. If you had an insensitive which could read to 10,000ft, its face has to show 0 - 10,000. Therefore the distances between any two markers (say 2000' to 3000') are small, and the markings for the hundreds of feet are close together, so it's hard to read. You might only get a marking for each 200'.

 

The sensitive altimeter only shows 1000' on its face. The face can have more marks, so each mark could show 20'. This gives the pilot more accurate information.

 

Both the sensitive and insesitive altimeters would read the same altitude if they were set to the same QNH.

 

Old Man Emu

 

 

[jakej]

Just to ad a bit to this conversation.You can still buy insensitive altimeters and they are about $300 less than sensitive ones. However what you must consider is the readability of the instrument. If you had an insensitive which could read to 10,000ft, its face has to show 0 - 10,000. Therefore the distances between any two markers (say 2000' to 3000') are small, and the markings for the hundreds of feet are close together, so it's hard to read. You might only get a marking for each 200'.

 

The sensitive altimeter only shows 1000' on its face. The face can have more marks, so each mark could show 20'. This gives the pilot more accurate information.

 

Both the sensitive and insesitive altimeters would read the same altitude if they were set to the same QNH.

 

Old Man Emu

Are you encouraging us to buy the cheaper types ? If yes, then please tell everyone that these can't/won't be 'signed off' by a maintenance org.