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Transponder/Static System Check IFR vs. VFR

aart wrote:

I am puzzled about that too, as it seems far more restrictive than what is currently done in most countries, and that cannot be the intent of a MIP.

I am a layman, and maybe I’m being ‘too creative‘, but here’s an idea:

AFAIUI, the MIP defines two types of checks. An ‘operational’ and a ‘functional’ one. Operational means it needs to work (as in a light bulb works or not), functional means it needs to pass a number of quantitative parameters.

I’ve come to the same conclusion. As far as I can see this isn’t spelled out anywhere, but given how the terms “operational” and “functional” are used (in the new part-ML at least) that’s the only reasonable interpretation. E.g. part-ML says that you should do a “functional test of the pitot-static system;” and it makes much more sense to do such a test using test equipment. Also, the knowledge requirements for a part-66 license consistently refers to “functional tests”.

Last Edited by Airborne_Again at 14 Jun 08:17
ESKC (Uppsala/Sundbro), Sweden

@Airborne_Again

you wrote:

The MIP says you should do operational checks on the pitot-static system and transponder every 100 hrs.

I am puzzled about that too, as it seems far more restrictive than what is currently done in most countries, and that cannot be the intent of a MIP.

I am a layman, and maybe I’m being ‘too creative‘, but here’s an idea:

AFAIUI, the MIP defines two types of checks. An ‘operational’ and a ‘functional’ one. Operational means it needs to work (as in a light bulb works or not), functional means it needs to pass a number of quantitative parameters.

Funnily enough the MIP uses the term ‘operational’ for the the TXP test, and not ‘functional’ which is what one would expect. So, how about doing an ‘operational’ test every 100 hrs, by just checking with ATC during a flight, and making a log entry? But in order to be safe, add a proper functional test every 2 calendar years. So you are doing better than the MIP

Last Edited by aart at 13 Jun 18:42
Private field, Mallorca, Spain

I am doing IR training and want to fly IFR in my F-reg and I’m going through the regulations. I have an approved maintenance program and it’s managed through a CAMO and is not ELA1 (1243 kg MTOW).

Regarding the bi-annual IFR checks, I believe this makes me fall outside the applicable aircraft given in P-14-15 of the DGAC document translated below. Can anyone confirm this is correct?:

Applicability:
All aircraft other than balloons not subject to a reliability program (*) and:
 operated in commercial air transport.
 operated in IFR.

(*) Reliability program as provided for in M.A.302 (f), developed and implemented by
Part M under Part G which manages the airworthiness of the aircraft

EIMH, Ireland

All the SSD120 encoders produce gray code output even if they also provide RS232 output. Depending on the transponder, it may or may not accept RS232 as input and may require the gray code parallel interface.

KUZA, United States

Peter wrote:

Could it be related to this?

That is what I thought that could be likely, it can not be the case however as Guillaume indicates he uses serial RS-232 instead of parallel gray code / Gillham code.

JP-Avionics
EHMZ

Could it be related to this?

Administrator
Shoreham EGKA, United Kingdom

Jesse wrote:

Such a big error, in such a small altitude difference is not likely to be caused by an out of tolerance / adjustment issue. It could very well be an failure on the encoder or wiring.

That’s exactly what I thought. My encoder (SSD120-30N-RS232) is still spot on from GND to FL140. I ruled out the wiring issue as it’s RS232 wired and values at other FL are very accurate / steady. The discrepancy starts from FL140+. I know this encoder can re-calibrated at each FL with a laptop. Maybe that would help ?
Thanks for the advice

Jesse wrote:

You don’t have to go the MIP route?

MIP brings a lot of good stuff too. Most CAA mandates TBO. Being able to IRAN a 300 hours in service propeller instead of an overhaul when reaching the 6 years limit saves quite a lot money. I already had to scrap three blades due to blade grinding during the overhaul (on a 2 blade prop). Propeller blades (used or new) are not cheap.
I’ve plenty of other examples in mind but that’s not the point.
IMHO, the MIP is great except this “transponder operational check” which should be mandated every two years (I’m not in favor of no check!).

Jesse wrote:

As the actual testing was allready done, the AD didn’t add cost when it came into force, and didn’t lower cost when it was revoked.

Actually, for F-reg aircraft, the AD cancellation added costs. While the AD used to target only “gilham wired” transponder for obvious reasons, the new “test” set-up after the AD cancellation was mandatory for every transponder / encoder.

Last Edited by Guillaume at 17 Feb 23:37

Airborne_Again wrote:

The MIP says you should do operational checks on the pitot-static system and transponder every 100 hrs.

In that case it is more strict then national regulations. The are other points as well. As in previouse post, I sometimes wonder what true benefits are for MIP, especially in those countries where national regulations allow on condition. I think all these regulations are much closer then often indicated. Similair as that testing between different countries isn’t that different.

JP-Avionics
EHMZ

Guillaume wrote:

Despite paying for the tests, 2 months later I climbed for the first time to FL150 and the altitude encoder was showing FL145 (while it was spot-on at FL140)…
It seriously makes you wonder if the tests were really done…

Such a big error, in such a small altitude difference is not likely to be caused by an out of tolerance / adjustment issue. It could very well be an failure on the encoder or wiring.

Guillaume wrote:

Anyway, the real “issue” I see is that so far we had a two year periodicity and now it’s being reduced from two years to one year.

You don’t have to go the MIP route? Sometimes the MIP can be more strict than current national regulations.I really fail to see the real benefits, and I think they are often over exaggerated.

One other example, was where AOPA-NL published, that AOPA had won the lobby against the AD2006-0265 encoder AD, and that the revoke of this AD would save owners lots of money. I responded to this as well, as it didn’t make sense. This AD required testing of the altitude encoder. Testing of the altitude encoder was allready part of testing on Dutch aircraft, before the AD, and still is afterwards, just like UK, Belgium, France, Germany and I guess most others. As the actual testing was allready done, the AD didn’t add cost when it came into force, and didn’t lower cost when it was revoked.

Altitude encoder issue should be sorted before the next flight. As indicated before, there is a good reason that all new transponder show the flight level, it is part of transponder design. Now you can at least check altimeter and flight level (remember 1013,25 mB) and recognize issues.

JP-Avionics
EHMZ

Jesse wrote:

I don’t understand, do you care to explain.

The MIP says you should do operational checks on the pitot-static system and transponder every 100 hrs.

ESKC (Uppsala/Sundbro), Sweden
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