Question:
 I know that Lancairs have been flying IFR for years, but they have
 certified engines, props and instruments.

 According to FAA rules, can rotary engined experimental with IFR
 instruments and IFR certified CS prop be registered as IFR-certified, or
 "IFR approved" ?

 Or should the engine be also IFR certified to start with, like eg.
 IO-360? This has some connections to PSRU project...

 Please comment. Did I forgot something?

 Cheers,
 Petri

 Question, what is an "IFR certified" powerplant or prop?

 C. Smith



  There is no IFR certification by the FAA of experimental aircraft. The
  standard operating limitations issued by the FAA for Experimental
  (Amateur Built) specify Day VFR operation "unless equipped for night
VFR
  and/or IFR in accordance with FAR section 91.205.  The
representative of
  the Administrator issuing the Airworthiness Certificate and
accompanying
  Operating Limitations may add any other limitations they feel necessary
  for safety, so it would be prudent to discuss this issue with the
  persons you consider to employ for certification of your airplane.
  Choose a DAR who is not antagonistic towards rotary power. Both my
  IO-470 powered RV-8 and my Subaru-powered (all-electric, fuel injected)
  RV-6 have the preceding language permitting IFR if equipped per Part
91.

  Victor Roberts


  I'm fully aware of all of this Victor, which is why I asked the
question,
  what is an IFR certified engine or prop.
  A "aircraft" is certified for operation as IFR, an experimental gets an
  airworthiness certificate with operating limitations.
  Powerplants and props get certification for use on certificated
aircraft,
  but I'm not familiar with the "IFR" bit as it pertains
  an engine or propeller, and would like to know more about this.
  Thanks.
  C. Smith

Hi,

My question could be set confusingly, I am not familiar with the
procedure how FAA gives permits for IFR flying for experimental
aircraft. I just know that it could and has been done.

That talk about IFR certifed prop and engine has it's origin on some
shady bits of information like "you cannot get IFR with xxx prop" and
"you need redundant systems to get a single IFR certified".

What's interesting is how auto engine conversion like rotary engine mix
with this - does 13B count as "sufficiently verified" design or should
one expect difficulties when trying to get that IFR certification.

Victor's reply implies that the result depends on the DAR's attitude.
(Designated Airworthiness Representative?)
Has anybody tried this yet?

Cheers,
Petri


My take is that if one is homebuilding for IFR (as I am) that one should
meet the requirements of 91.205(a) thru (d), provide documentation
and evidence for proper grounding of all airframe components (those of
you
with composite airframes, good luck), and have a sound design plan for
the
aircraft systems with redundancy that provides for
the same contingencies that a certificated aircraft would need. Not
having
heard of restrictions for xxx prop, I cannot comment. But redundant
systems
is simple enough.
However the elements of redundancy all depend on what you choose, and how
you do it. Not enough detail to answer.
I think that, so far, all of our discussions have indicated that: the
fuel
injection system has both double redundancy with injectors, control
circuitry, so all one would need to add is design an electrical system
with
redundancy, see the aeroelectric connection for the myriad ways to
skin that
cat.
Hopefully the ignition system when finished and tested will meet the same
concerns, we already have 2 plugs per rotor.
In the end, one has to make sure that during the certification
process, you
let the inspector know what you want to be able to do. If they have
issues,
they should be able to tell you what they are, you go back to the drawing
board, and make changes as necessary to satisfy the requirement. Being
familiar enough with your systems as designed, and articulate enough
to be
able to explain to the inspector how your systems will operate and be
backed
up in various failure modes is what you need to be able to do.
What they don't want is for a single failure to cause you to fall out
of the
sky, or create so much distraction that you cannot complete an instrument
approach. Demonstrate this, and I think you will win.
I've attached the latest revision of AC20-27G for everyone's reference.
Sorry it is big.
C. Smith



Dual ignition is not a hard requirement. My Subaru has only one plug per
cylinder. That is why it matters how you select your DAR. Once you apply
for your certification, only the DAR or FAA office you applied to can
complete the certification. You will have to comply with their
requirements and/or accept their limitations, there is no appeal and you
cannot withdraw your application and apply anywhere else.

Victor Roberts