Non TSO'd instruments in certified aircraft

[Piloto]

Quote: peter

I know of no other part 23 EFIS system that can make the same claims.

[N601RX]

Although interesting, this post has changed from the origninal question that was asked. Check out this dynon unit for $1600.  If legal it would make an affordable backup. On second thought it uses a standard 3-1/8 instrument hole and has it's own rechargable battery which will last for 2 hrs.  What if you didn't actually mount it, susposed you just had an empty hole with some velcro around it and just slid the instrument in when before going flying.  It would not actually be installed, so would it be illegal?  Seems to me it would then fall into the same catagory as a portable GPS. The airspeed would not work, but. 

www.dynonavionics.com/docs/D6_intro.html

 

 

[M016576]

Quote: N601RX

Although interesting, this post has changed from the origninal question that was asked. Check out this dynon unit for $1600.  If legal it would make an affordable backup. On second thought it uses a standard 3-1/8 instrument hole and has it's own rechargable battery which will last for 2 hrs.  What if you didn't actually mount it, susposed you just had an empty hole with some velcro around it and just slid the instrument in when before going flying.  It would not actually be installed, so would it be illegal?  Seems to me it would then fall into the same catagory as a portable GPS. The airspeed would not work, but. 

www.dynonavionics.com/docs/D6_intro.html

 

 

[M016576]

Quote: Piloto

I know of no other part 23 EFIS system that can make the same claims.

[tony]

That’s exactly why some instruments are driven by vacuum while others are powered by electric.  That’s not an accident, that’s by design.  When you do the Functional Hazard Assessment (FHA) you’ll soon find out that the electrical system is a single point failure and can never support catastrophic events.

 Furthermore I haven’t seen a single STC for an EFIS device that did not include the vacuum supported functions installed with the old instruments in the panel as well.

[Piloto]

Even the later G1000 Mooneys that have dual alternator, dual battery and separate buses kept the air speed indicator and the altimeter. No matter how reliable the Aspen is it still relies on a mechanical source (the alternator) for power. On the other hand the air speed indicator the altimeter and compass are self sufficient for indefinite time and its simple and proven mechanism makes them more reliable than any electronic instrument. Not having airspeed indication can turn into a catastrophic situation specially on landing.

José 

[peter]

Quote: Piloto

Would you need to have dual alternator for the above? Coming from Santa Maria (LPAZ) to St John's (CYYT) I lost the alternator in IFR conditions at 400nm from LPAZ. I had to shutdown all the electrical systems to save battery knowing that I would need to make an ILS approach to minimums at CYYT. Luckily this plane had vacuum driven ADI and heading gyros that I was able to use for the next 7 hours of flight. I only needed to turn electrical power on once an hour for GPS position fix and HF position report. I was able to land at CYYT in IFR conditions with no event. The electrical problem turned out to be a loose belt tension bolt on the alternator. Having a long duration alternate power source is a must if you want to continue having the existing redundancy you have with vacuum gyros.

[peter]

Quote: tony

 Furthermore I haven’t seen a single STC for an EFIS device that did not include the vacuum supported functions installed with the old instruments in the panel as well.

[peter]

Quote: tony

When you do the Functional Hazard Assessment (FHA) you’ll soon find out that the electrical system is a single point failure and can never support catastrophic events. 

[Piloto]

Quote: peter

Wow, that's quite a leg - nearly 1400 nm.  I used to fly that leg when I flew C130's for Canada.  It's not something I think I would want to do single engine.  Do they still require special equipment and crew training requirements before they will let you launch on these long over water legs single engine? 

I'm curious, why proceed a 1000nm ahead, when your departure airport was 400 nm behind you, and other airports in the Azores were even closer?  I'm not sure I would have made the same decision.

To answer your question; no, a second alternator and ship’s battery is not required; but a dedicated emergency backup battery is.  For folks who want to removed backups, Aspen has an emergency backup battery (which is an externally mounted unit) which provides 2 to 3 hrs of reserve power for the backup display should ship's power fail.  The regulations require 30 minutes of reserve power so the Aspen set up exceeds that several times over.  However, if I was going to launch on a 9 hour over water leg, I might want to make sure I had more than 30 minutes of reserve electricity if my single alternator failed. 

 

[peter]

Quote: Piloto

Question: Does the emergency battery duration limits how far I can fly from suitable landing site? Like if I am a charter flying to Bermuda or the Azores at night what would be the procedure after the battery runs down and I have no stand-by instruments. As you surely knows battery charge duration is much less after a few years of use. 

[M204ever]

The Airliners back-ups are electronic types which have to meet DAL A, price is double G500 or triple EFD1000 meeting DAL B only.

Aspen or Garmin PFD/MFDs aim on GA and given installed correctly! add more safety to the aircraft than anything else. It is not just the ADI,AS or ALT display, its the data link capabilities as well. The integration of all onboard avionics is the benefit.

These installations should never be compared with a panel mounted G696 or a Dynon EFIS. If fixed to the aircraft or supplied from that power they have to be certified, too, which isn't worth.

Bernd

[1964-M20E]

My question regarding TSO, PMA certified vs. non certified is this.

 

Is it safe or not?  If it is safe to be placed in an experimental type then why not in a certified type?

The experimental if flying around just the same as the certified type sometimes higher and faster than most certified types.

[Piloto]

Peter

Thanks for that excellent reply. I shows that you know the subject. I never expected a B777 or A380 to have vacuum driven stby gyros. But in view that they have more than one alternator that they still decided to put the battery backed stby instruments. I feel more confortable keeping my old trusty pneumatic airspeed indicator than a battery backed one. No need to worry about running out of juice.

José  

 

[Vref]

The B777 and A380 do not use mechanical pneumatic instruments or vacuum driven attitude indicators. They each have electronic standby's that are powered from an emergency bus, which is the same architecture used by Aspen.  

[Guillaume]

Quote: Vref

mmmh don't know the 380 and 777 but for sure on the 320's and 330, 340's the STBY Altimeter and airspeed instruments are pneumatic...ATA 31 indicating and recording will tell you....

The ATT indicator is more and more an electronic display with internal electronic gyro...connected to the battery bus if all stuff is dead....Used to teach this EIS ATA 31 and redundancy....

[Geoff]

Although interesting, this post has changed from the origninal question that was asked. Check out this dynon unit for $1600.  If legal it would make an affordable backup. On second thought it uses a standard 3-1/8 instrument hole and has it's own rechargable battery which will last for 2 hrs.  What if you didn't actually mount it, susposed you just had an empty hole with some velcro around it and just slid the instrument in when before going flying.  It would not actually be installed, so would it be illegal?  Seems to me it would then fall into the same catagory as a portable GPS. The airspeed would not work, but. 

www.dynonavionics.com/docs/D6_intro.html

That was the equipment that prompted the original question. 

[peter]

Quote: 1964-M20E

My question regarding TSO, PMA certified vs. non certified is this.

 

Is it safe or not?  If it is safe to be placed in an experimental type then why not in a certified type?

The experimental if flying around just the same as the certified type sometimes higher and faster than most certified types.

[Vref]

Quote: Guillaume

On the latest Airbus A320 series the RMI seems to be the only analogue instrument. Even the backup ADI (wich include Altimeter Airspeed and ATT) is now on a LCD screen.

[Carl S]

Quote: peter

Not allowed.

Instruments that perform a function where the function is required by the rules (as opposed to functions that are not required by the rules, like a GPS map) must be approved instruments - e.g. TSO or PMA with installation approval.  An uncertified EFIS, even if placarded as "supplemental", is considered to be of such a compelling nature that it would be the de facto primary instrument, and not supplemental. 

[peter]

Quote: N223MM

What if the secondary EFIS were out of the pilot's direct line of site?  I ask because this looks like it is in a certified aircraft. Or, maybe this was done before the memo that was mentioned came out? 

[DaV8or]

Quote: peter

I'm not familiar with this aircraft cockpit - is it possible that it is a warbird, or a public use aircraft. Neither of those classes of aircraft need to comply with the FARs.

[Carl S]

Quote: peter

Neither the memo, or FAA order 8900.1 speak to where the EFIS is installed when saying an STC is required.  I suppose you could seek an STC to install the uncertified device in the copilot panel, and see if FAA engineering agrees if a device in that location needed not have a TSO.

I'm not familiar with this aircraft cockpit - is it possible that it is a warbird, or a public use aircraft. Neither of those classes of aircraft need to comply with the FARs.

 

[tony]

Let’s try and get this back on topic for Geoff.  The posting on the board touches on a question that the FAA remains silence on.  I think it’s really time for them to come out with an advisory circular or a position on this issue.  I personally believe they are remain silent because if they require all flight instruments to be compliant with a TSO, most of the flying aircraft out there will no longer be airworthy.  Again, if someone finds the regulation or requirement I’d love to read it.    

A TSO is NOT a requirement for Part 91 aircraft. It may be required for aircraft under part 135 or for certain types of equipment such as transponders, ELTs, or IFR GPS units which is a requirement to gain access to specific types of airspace.  What a TSO is however is a manufacturing standard.  It is not an airworthiness standard.

Our Mooney’s, including the last one that came out of the factory, are certified under CAR-3.  If you Google “cert basis M20” you can read all of the amended type certs that have been done on all the models over the years.  The cert basis is from August 1955.  I’m sure it was equipped with basic instruments (altimeter, airspeed, heading) that were NOT TSOed. In fact, the standard did not exist at the time and FAR Part 23 does not supersede the certification basis.

FAR 91.205 (operating and flight rules, Subpart C--Equipment, Instrument, and Certificate Requirements) defines what equipment is required for operation of a civilian aircraft with U.S. airworthiness certificates.  I can’t find anything in there that requires any of the instruments to be TSOed. In fact, most of the GA aircraft out there continue to fly with just the basic equipment listed and they are perfectly airworthy without them.

Now to get back to Geoff’s original question, FAA approval is still required to install equipment in a certified production aircraft. Thanks to the link that Rogerl provided, this can be done by a field installation using a 337 submitted by a licensed A&P or AI.  The process I thought was explained very well on pages 25 -27 of that publication and complies with AC 43-9c.

I also found a reference in the document that Peter quoted:  In 8900.1, volume 4, chapter 14, section 2 titled Evaluate Avionics Equipment Approval.  It stated that the instrument or equipment approval can be accomplished by the use of a Technical Standard Order (TSO) or,  Acceptance as part of the aircraft on the original Type Certificate (TC) or Supplemental Type Certificate (STC), or Parts Manufacturing Approval (PMA), or Field approval (FAA Form 337, Major Repair and Alteration).

Therefore (and this my opinion only) I think installing a non TSO’d device in the aircraft is authorized as long as it does not replace any of the equipment that changes the cert basis and is installed with a 337.

I know some A&P's simply aren't willing to assume the liability for a non-TSO installation. And some simply fall back on the generalization that TSO equipment is required in a production aircraft. But I have yet to find anything that specifically prohibits installing a non-TSO part in an aircraft operated under Part 91 (with the exceptions noted).  Now all Geoff needs to do is find an A&P that agrees with me.

 

 

[tony]

Precisely.  The FHA and associated System Safety Assessment (SSA) tell the story. The FAA has very stringent rules that must be met to ensure no single failure, or probable combination of failures, can lead to a catastrophic fault, such as loss of attitude information.  For catastrophic failures, their experts pour over the SSA and challenge every assumption, and require that every conclusion and number be supported. 

This is the hardest part of certification.  It is not an easy thing to do.

This is a great conversation over a beer.  Peter you are right, but lets not forget 25.1309 which says.  There shall be no single element in the design that,if it fails, an maifest itself as a catasptophic event.  Isn't the DO-178B software thats in your displays an element?  Perhaps we should just keep those airspeed, altitide and attitiude indicators just to mitigate the hazard?