IFR Certs

Llewtrah381

Llewtrah381

Pattern Altitude
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Apr 9, 2010
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Llewtrah
Having just written another check for another 2-year cert, and having chatted with the guy while doing it, I wonder if this is a “tradition” ripe for reconsideration.

Even my 1977 analog altimeter was well within specs and the new GI275 was rock solid, of course. I wonder, for example, if altimeters which are digital and built after a certain date plus transponders without cavity tubes and built after a certain date could go to - I dunno - a 5-year cert, at least for certified instruments.

Seems like we’re way more likely to learn of a failed/failing instrument from ATC than at a 2-year check.

ADD: as a different aside, I asked him if it was possible to check the airspeed indicator. On the 275, I think it was a matter of him changing screens on his magic box. But now I know how close to reality my IAS is (on the 275, it reads about 2kt high). Something one may consider asking about when getting the cert done, if only for curiosity.
 
My AI was 10 knots low…..it was overhauled as a result of this check. Several years ago the altimeter did fail. So it is useful if you need to rely on those instruments. ;)
 
Checkout_my_Six said:
My AI was 10 knots low…..it was overhauled as a result of this check. Several years ago the altimeter did fail. So it is useful if you need to rely on those instruments. ;)
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Were they new electronic ones or legacy analogs?
 
Yeah - 2 years for old stuff is actually generous in some cases, I’d bet. But the new stuff uses different technology and probably has different failure modes with probably less frequent failures. That’s why I’d suggest they let new electronic stuff go longer but keep 2 years for older.
 
I always check mine before the shop sees it. I tape off the static ports and apply a vacuum to the system and climb the alt 2,000 feet AGL. It needs to hold that with a max of 100 fpm for a minute to pass.
 
You mean you got a IFR pitot static check?

Seeing how dependent people have become on their TV screens with ADSB, I sure hope it’s reporting correctly

I would say do a eye tracking test, during a VFR BFR the CFI also fills out a box on where the airman looks when there is a traffic call, if it’s eyes down on his screens, check box A, if it’s out the window, check box B

If box A is checked the system check needs to be now done every 6mo and they need to always have the newest model of equipment, as it’s the only thing actually looking for traffic

If box B is checked just the normal 2yr check

Frankly I haven’t seen a huge difference in problems between the older more simple systems and the newer ADC type systems
 
Llewtrah381 said:
That’s why I’d suggest they let new electronic stuff go longer but keep 2 years for older.
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You'll find 91.411/413 IFR checks are based more on international standard requirements which the FARs also service from a regulatory standpoint.
 
Bell206 said:
You'll find 91.411/413 IFR checks are based more on international standard requirements which the FARs also service from a regulatory standpoint.
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Aah. Still - maybe time for them to revisit.
 
Checkout_my_Six said:
I always check mine before the shop sees it. I tape off the static ports and apply a vacuum to the system and climb the alt 2,000 feet AGL. It needs to hold that with a max of 100 fpm for a minute to pass.
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The leak down test he did for mine was at 18K and it did well. He said the most common reason for failure was a bad o ring at the stem for the Kollsman. I wonder how many o rings are in a 275, etc…
 
Llewtrah381 said:
The leak down test he did for mine was at 18K and it did well. He said the most common reason for failure was a bad o ring at the stem for the Kollsman. I wonder how many o rings are in a 275, etc…
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Yup. He takes mine well into 20k. Mine is a turbo. And that pretest helps identify gross leaks.
 
Llewtrah381 said:
Aah. Still - maybe time for them to revisit.
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from a social engineering pov - it would be more likely to succeed if some other country (e.g., France) came up with the idea on their own (or at least thought they did).
 
Bob Noel said:
from a social engineering pov - it would be more likely to succeed if some other country (e.g., France) came up with the idea on their own (or at least thought they did).
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True statement.

Even so, it still seems plausible for Part 91 staying in the US - kinda like UAT
 
I might guess, that although an aircraft may have newer digital instruments and transponder installed, (with perhaps a greater mean time between failure), they are very likely to still be hooked up to 40-year old plastic or rubber tubing that could crack, leak, etc.
 
Jim Carpenter said:
I might guess, that although an aircraft may have newer digital instruments and transponder installed, (with perhaps a greater mean time between failure), they are very likely to still be hooked up to 40-year old plastic or rubber tubing that could crack, leak, etc.
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True but watching him do it yesterday, that part is never tested if it’s done “properly”. He completely removed the altimeter and did the test outside the plane. For the 275, he undid the quick connect to the tubing and tested it in the panel but without the lines. (All of my tubing was replaced when the 275s went in with new stuff (LLDPE?), with the nice quick-connects).

Some people test via the pitot tube but I’ve heard that’s not a good practice. That WOULD detect leaks, though.

But yeah, testing 40+ year old tubing would make sense. But I’m not going to suggest it to the FAA… ;)
 
Llewtrah381 said:
Even so, it still seems plausible for Part 91 staying in the US - kinda like UAT
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Except there have been numerous aircraft running digital systems for quite some time with no hint of any changes to the 2 year interval and they would be the ones to request it. However, just because its digital doesn't mean they don't have their own issues as well. At least in my experience.
 
and there's a pretty good chance that you'll spring a leak in one of those dozens of plastic fittings on that +40 yo airplane. That's a common culprit.
 
Llewtrah381 said:
Having just written another check for another 2-year cert, and having chatted with the guy while doing it, I wonder if this is a “tradition” ripe for reconsideration.

Even my 1977 analog altimeter was well within specs and the new GI275 was rock solid, of course. I wonder, for example, if altimeters which are digital and built after a certain date plus transponders without cavity tubes and built after a certain date could go to - I dunno - a 5-year cert, at least for certified instruments.

Seems like we’re way more likely to learn of a failed/failing instrument from ATC than at a 2-year check.

ADD: as a different aside, I asked him if it was possible to check the airspeed indicator. On the 275, I think it was a matter of him changing screens on his magic box. But now I know how close to reality my IAS is (on the 275, it reads about 2kt high). Something one may consider asking about when getting the cert done, if only for curiosity.
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So if I fly the plane VFR for 3 years and don’t ever speak to ATC, how do you know the airspeed indicator doesn’t have a dynamic (total) pressure leak into the static side of the instrument on the day you fly in IMC and bust an assigned altitude?
 
Clip4 said:
So if I fly the plane VFR for 3 years and don’t ever speak to ATC, how do you know the airspeed indicator doesn’t have a dynamic (total) pressure leak into the static side of the instrument on the day you fly in IMC and bust an assigned altitude?
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Given how the biennial check is done, how would you know that was happening even if you got it checked monthly? They test the altimeter on the bench - not plumbed in the system. At least that’s how it should be done, from what I’ve heard. I’ve only had one shop not physically remove the altimeter: they tested it via the pitot/static mast and that surprised me. They’re now out of business, incidentally.

To my knowledge there is no requirement to test the plumbing - ever. Only the altimeter (and not the ASI or VSI that I know of). That said, it seems like the plumbing is more likely to fail than the altimeter.
 
Llewtrah381 said:
To my knowledge there is no requirement to test the plumbing - ever.
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FYI: The static system check is a requirement for the altimeter test and noted in both 91.411 and 43 Appx E. Its also the only part of the 411/413 checks that an A&P can perform. As to testing the altimeter outside the aircraft there is no requirement and is usually a shop level preference. In my experience, I've seen more transponders bench tested vs altimeters given the ease of removal/install.
 
Bell206 said:
FYI: The static system check is a requirement for the altimeter test and noted in both 91.411 and 43 Appx E. Its also the only part of the 411/413 checks that an A&P can perform. As to testing the altimeter outside the aircraft there is no requirement and is usually a shop level preference. In my experience, I've seen more transponders bench tested vs altimeters given the ease of removal/install.
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Yup....note the usage of the word "system".... ;)
 
I’ve dropped the plane off for checks and come back a few hours later, with the explanation that they need to remove the altimeter to do the check. One time it was really quick and it turned out they did the test via the pitot tube. This time, I hung around and chatted w the Avionics guy while his son (recently certified to do the checks) did all the work. When he was putting the altimeter back in, I went to lunch with a friend. I obviously missed the rest of the process, even though I thought they were buttoning up.

Yeah - my mistake. Sounds like they also check the plumbing, which I missed and wasn’t specifically mentioned. Yeah - 5 years would be long.
 
Note....that the static "system" needs to be checked each time the static "system" is broken. The only reason to remove individual devices in the static "system" is to rule out potential items that may be leaking. In the +30 years I've been a certified A&P I've never witnessed the avoinics shop removing devices during a static check....unless they suspected that device as faulty. ;)
 
I've seen it done both ways. The infuriating one was the old (Colgan-era) Capital at HEF who took out my altimeter and claimed it didn't pass. I bristled a little bit at having to buy a new one and even more when they charged me to install it (which would have had to be done with the old one if it had passed) and then the core mysteriously disappeared (Margy wanted it for her aviation classes).

One shop let me sit with them while they walked me through the old style altimeter test, taking it up and down and measuring things like hysteresis, etc... My last one the guy connected up some sort of gizmo to my static system that had a tablet that automatically ran through the whole thing all he had to do is note the readings from the actual gauge face (still installed in the aircraft).
 
Llewtrah381 said:
Given how the biennial check is done, how would you know that was happening even if you got it checked monthly? They test the altimeter on the bench - not plumbed in the system. At least that’s how it should be done, from what I’ve heard. I’ve only had one shop not physically remove the altimeter: they tested it via the pitot/static mast and that surprised me. They’re now out of business, incidentally.

To my knowledge there is no requirement to test the plumbing - ever. Only the altimeter (and not the ASI or VSI that I know of). That said, it seems like the plumbing is more likely to fail than the altimeter.
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Exactly how do propose certifying an altimeter installed in a pressurized aircraft if you aren’t checking the static system for leaks?
 
Llewtrah381 said:
To my knowledge there is no requirement to test the plumbing - ever. Only the altimeter (and not the ASI or VSI that I know of). That said, it seems like the plumbing is more likely to fail than the altimeter.
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Not quite true. You have to do a leak down test on the entire static system to detect holes in it. I failed this on my last test. The line from one of the static ports had failed. It would have been an inconsequential error (as the other port was still connected and it was just leaking into the fuselage) but it was tested.

The static inspection is required to be redone any time the system is opened or otherwise possibly compromised.
 
rotormatic1 said:
Pitot and static system leak check should be done at annual inspection…
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Says who? This is not in the scope of the annual inspection in 43axD nor have I ever seen it on any annual checklist of a plane I've owned. In fact, there's nothing in the IFR certs that mandates a check for leaks in the pitot system nor have I ever seen it done (unless the airspeed indicator is so leaky that it affects the static system).
 
Instruments—for poor condition, mounting, marking, and (where practicable) improper operation.
 
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