IFR cert with 20K altimeter

[Vince Hoffart]

All,

I'm up for my IFR cert in my newly acquired PA 24-250. It has an altimeter that is certified to 20,000 so my shop won't certify it because the 250 has a ceiling of 27,000-29,000 according to POH.

Has anyone encountered this issue before?

Ideas for where to get a proper Overhauled or new Altimeter?

[Larry Martin]

Do you have a pressure suit and pressure breathing mask!?

I don't see why he needs to certify the sytem beyond the limits of the components themselves. I may be at a "good" shop today and will ask. I'm fortunate, as we have several shops to choose from - I would not use that shop. OTH, I hope that I am not eating crow after I talk to my shop!

[Larry Martin]

Vince,

I am here to eat crow. The shop is correct - if the airplane can go higher than the altimeter then they can not certify it. I don't have the FAR handy. OTH, our local Comanche expert at Heritage thinks that the altitude is a misprint.... possibly 20k, but not higher and even doubted 20k. (We didn't have books handy)

[Timothy Quigley]

[Vince Hoffart]

Thank you Larry and Timothy for your response.

I have two separate POH's and both show absolute ceilings of >25,000 depending on weight.

I will try another shop though as I'm frustrated with not getting a hard cost to budget with from the shop. The endless hours of troubleshooting cost me $ significantly over expectations for hooking up two wires to my Garmin 530w as well as looking for pitot leaks.

[LeWayne Garrison]

In my opinion I would find a new shop. My 1959 250 is has a service ceiling of 20,000 feet and an absolute ceiling of 21,000 ft. Never had an issue with a 20,000 ft altimeter.

[Zach Grant L1011jock]

I corresponded with Vince on this, but the answer is not as cut and dried as it may seem on the surface. CAN the aircraft go higher, yes, however you are in Class A airspace at that point anywhere in the continental US. Thus you are going to be IFR, and as such must have a certified altimeter/Static system/encoder. That system can be certified to a value of 20K'. That is now your maximum allowable flight level as the certification of required components are such that they are the most limiting factor. An aircraft may have a certified ceiling of 25000' such as is the case with our turbocharged aircraft. IF you don't have O2 onboard you are limited to 14000' domestically as a maximum altitude (for 30 min), and 18000' if you have O2 but only a nasal canula. These systems limit the maximum certified level of the aircraft by their certification (or regulation), it is no different. Also, performance charts in a POH are not regulatory in any manner. They are marketing graphics in reality, until you get to the certified charts required in FAR 25 aircraft. The only limitations of the aircraft exist in the FAA Approved AFM, which is the stack of paper that you may have forgotten about somewhere in a seatback pocket (contains limiting airspeeds, powerplant and instrument markings, CG limits, operational limitations, and required placards). It is also ONLY Section 2 of the ICS AFM/POH (and any required suppliment you may have based on equipment. Autopilots, nav systems, oxygen, alternators etc., all come with an AFM suppliment). Anything that doesn't say FAA approved is just advisory. Next, we can look and see in the TCDS that the certification standards for the aircraft are CAR 3, NOT FAR 23, so applying FAR23 certification regulations retroactively is improper. A quick perusal of a 1961 250 limitations section I have in front of me yields no maximum certified altitude listed in limitations, nor does the TCDS have any max altitude limit specified for any Comanche aircraft other than the turbocharged 260 and twin. Does that mean the altimetry needs to be certified to infinity on all non turboed models? Of course not. Whatever you certify the unit to is your new certified ceiling as there is no other number published.

Zach