Hi John, I believe your opinion and mine as to the absence of clear and enforceable regulatory requirement regarding replacement or supplementation of non-TSO equipment are in general agreement.
Other comments interspersed below. WRB On Mar 10, 2009, at 13:44, John Cooper wrote: > I have remained mute on this subject up till now because I really > don't know > what the answer is. And I hate to admit that... Me too. > > However, here's my opinion.... > > The altimeter is a required instrument, per FAR 91.205. Therefore, it > must > meet some minimum criteria. That criteria would logically be the non-TSO accuracy required by the least accurate altimeter ever installed in production Ercoupes by a manufacturer for any given model. > For example, you could not install a Timex > watch with an altimeter function, even though it read out in feet. > Neither > could you install one you got from Sharper Image for your car, even if > it > cost more than the TSO version. Where is this written? In the absence of information as to accuracy of the least accurate altimeter ever installed (see above), I would believe one could reasonably research, confirm, and substitute criteria for the least accurate altimeter ever installed (see above) in any CAA-approved certificated airframe from 1940 until TSO cane into effect, showing that the Chin Wah altimeter from Wig Error meets or exceeds such accuracy (which, after over fifty years of manufacturing experience and improvements it almost certainly would...those Chinese MIGS in Korea found our Sabres at altitude near the Yalu River just fine). This is the "equal or better" performance approach. Even among TSO radios, as an example, there is no regulation requiring pilot-owners to buy only the absolute best available (for obvious reasons). > > The Erco drawing calls for an Aeromarine 520N altimeter. So, for > sure, that > is a suitable instrument. Obviously, it was not TSO'd as the concept > didn't > exist then. So, what constitutes a suitable replacement? Or, put > another > way, is the Chin Wah altimeter from Aircraft Goose for $200 a suitable > replacement? The answer is "it's up to the installer", I think. Impossible not to agree. I would, however, point out that in times past many transponders were installed legally without altitude encoding capability; and that FAA approval or periodic re-certification of few, if any, of these installations required replacement of a functioning (and perhaps original) non-TSO altimeter with a TSO'd one. > Ultimately, the A&P who signs off the install, or, absent that, the IA > who > signs off the next annual, (or the last annual if you as the owner > sneak the > thing in between annuals) will be held responsible for it. There IS a difference between those A&Ps and IAs who look at who chooses them and signs their "pay check" and those who look at the agency that approved their credential to practice aviation maintenance before making their own personal decision as to whom their expertise and loyalty is owed. > Now, lets assume > you are involved in a mid air collision with an oncoming IFR Bonanza > at 6000 > feet. The wreckage of you plane reveals a Chin Wah altimeter stuck at > 5500. > Who's to blame? Most likely the pilot that did not re-set his altimeter according to applicable FARs ;<) > > Bottom line, If I'm installing that altimeter, I want some assurance > it is > an aircraft quality part. The TSO is that insurance. Your IA may view > it > differently, assuming he knows what he's looking at... I agree that different persons have different priorities and resources. Any question as to FAA authority, wisdom and necessity to limit access to "OUR" sky by citizens of more limited means willing to carefully and responsibly assess any quantifiable "risk" of relying on non-TSO equipment is not going to be properly addresses in this thread. Regards, WRB -- > > John Cooper > Skyport Services > www.skyportservices.net > > > > > ------------------------------------ > > Yahoo! Groups Links > > >
