Minimum Instruments Required?

Greetings all,

I know this must've been discussed here before, but I couldn't find anything
definitive one way or the other when searching with Google.

A friend who's starting an amateur-built experimental aircraft project
recently emailed me to ask if there's a list of the *minimum* required
instruments he must have installed in order to obtain an airworthiness
certificate.

I did a little research and came to the conclusion that no, if you intend only
to operate non-aerobatic flight under Day VFR conditions, there's no
regulatory requirement to have any instrumentation whatsoever.

Now don't get me wrong here, I'm not suggesting having no instruments
installed is a good idea. Not only that, it would undoubtedly attract the
attention of an airworthiness inspector and create difficulties. During the
airworthiness inspection of my own aircraft several years ago, the FAA
inspector didn't look at or say anything about the instruments I had
installed... and I don't have the full compliment spelled out in 91.205.

The basis for my conclusion of not being required to have any instruments...

FAR 91.205 "Powered civil aircraft with standard category U.S. airworthiness
certificates: Instrument and equipment requirements." gives a list of required
instruments for various types of flight. However, it applies ONLY to civil
aircraft with a "standard" category airworthiness certificate.

It states:

"(a) General. Except as provided in paragraphs (c)(3) and (e) of this section,
no person may operate a powered civil aircraft WITH A STANDARD CATEGORY U.S.
AIRWORTHINESS CERTIFICATE in any operation described in paragraphs (b) through
(f) of this section unless that aircraft contains the instruments and
equipment specified in those paragraphs (or FAA-approved equivalents) for that
type of operation, and those instruments and items of equipment are in
operable condition."

An amateur-built experimental aircraft is issued a "special" airworthiness
certificate (not a "standard" airworthiness certificate):

"Section 21.175: Airworthiness certificates: classification.

(a) Standard airworthiness certificates are airworthiness certificates issued
for aircraft type certificated in the normal, utility, acrobatic, commuter, or
transport category, and for manned free balloons, and for aircraft designated
by the Administrator as special classes of aircraft.

(b) Special airworthiness certificates are primary, restricted, limited,
light-sport, and provisional airworthiness certificates, special flight
permits, and experimental certificates."

Interestingly, FAA Order 8130.2D directs FAA inspectors and DARs to verify any
installed instruments are marked appropriately, and maintained properly (via
the operating limitations) but it doesn't require compliance with 91.205...

"SECTION 7. EXPERIMENTAL AMATEUR-BUILT AIRWORTHINESS CERTIFICATIONS

128. CERTIFICATION PROCEDURES. The procedures in this chapter provide guidance
material associated with airworthiness certification and the issuance of Form
8130-7.

c. Aircraft Inspection. The FAA shall arrange with the applicant to make the
aircraft available for inspection to determine that:
(1) The identification plate meets the requirements of § 45.11, as applicable.
(2) The information on the identification plate is correct, matches the
information on Form 8130-6, and is in accordance with § 45.13, as applicable.
(3) The aircraft nationality and registration marks are in accordance with
part 45, subpart C, Nationality and Registration Marks.
(4) The flight control system, engine(s), propeller(s), pitot static system,
and ASSOCIATED INSTRUMENTS operate properly.
(5) The INSTRUMENTS ARE MARKED APPROPRIATELY.
(6) An emergency locator transmitter (ELT) is installed, if required (§
91.207).

134. ISSUANCE OF EXPERIMENTAL AMATEUR-BUILT OPERATING LIMITATIONS.

(9) Aircraft instruments and equipment installed and used under § 91.205 must
be inspected and maintained in accordance with the requirements of part 91.
Any maintenance or inspection of this equipment must be recorded in the
aircraft maintenance records."

Also, if you intend to use your experimental aircraft for exhibition or air
racing, then according to FAA Order 8130.2D, you DO have to comply with
91.205...

"140. SPECIAL CERTIFICATION REQUIREMENTS. The following provide information
and guidance concerning airworthiness certification for experimental aircraft
for the purpose(s) of exhibition and/or air racing. These steps are in the
normal order of occurrence for the certification of these aircraft.

c. Aircraft Inspection. The FAA will perform an inspection to the extent
necessary to ensure that an inspection of the aircraft and aircraft systems
has been accomplished in accordance with the inspection requirements
as identified in paragraph 88b of this order. Additionally, the FAA will
verify that instruments, instrument markings, and placards are as required by
the CFR and are identified in the English language. Verify that all
measurements are converted to standard U.S. units of measure for those
instruments necessary for operation in the U.S. air traffic system.

NOTE: Depending on the intended operation, the applicable reference would be
§ 91.205(b), VFR (day); § 91.205(c), VFR (night); or § 91.205(d), IFR.
Operators should be alerted that there are specific requirements under part 91
for maintenance and inspection of the various aircraft instruments, and that
those requirements are applicable for these aircraft if the instruments are
installed, e.g., §§ 91.173 through 91.187, 91.215, 91.217, 91.219, 91.411,
91.413, etc."

Best regards,

John L.

The Bleriot currently being built by Evergreen museum in McMinnville has
about 2 instruments. Oil pressure and temperature, I think. Maybe a
sight glass for fuel.

John A. Landry wrote:
Greetings all,

I know this must've been discussed here before, but I couldn't find anything
definitive one way or the other when searching with Google.


--
J Kimmel

www.metalinnovations.com

"Cuius testiculos habes, habeas cardia et cerebellum." - When you have
their full attention in your grip, their hearts and minds will follow.

John A. Landry wrote:
Greetings all,

I know this must've been discussed here before, but I couldn't find anything
definitive one way or the other when searching with Google.

A friend who's starting an amateur-built experimental aircraft project
recently emailed me to ask if there's a list of the *minimum* required
instruments he must have installed in order to obtain an airworthiness
certificate.
snip

I thought the minimums were something like:
Tachometer (1 per engine)
Oil pressure
Mag compass
Altimeter
Temperature (for liquid-cooled)
Oil temp (for air-cooled engines
Fuel quantity (1 per tank)
Lights (anticollision)
Airspeed
Manifold pressure (if constant speed prop)
ELT
Seat belts

That sounds about right as far as I can remember, except, I believe the
ELT is not required if the plane is single place and I don't think
lights are required if the plane is to be registered for day VFR only.
But this doesn't address Mr. Landry's issue of "standard" vs "special"
certificates.

Neal

On 14 Oct 2005 10:07:34 -0700, in rec.aviation.homebuilt,
said:

But this doesn't address Mr. Landry's issue of "standard" vs "special"
certificates.

Neal,

I guess I made my post because I was looking for supporting or consenting
opinions from the group as to whether I can to a correct conclusion in trying
to interpret the FAR's.

of course I realize each FAA FSDO or MIDO would have their own interpretation
(don't they always)?

Best regards,

John L.

John A. Landry wrote:

On 14 Oct 2005 10:07:34 -0700, in rec.aviation.homebuilt,
said:

But this doesn't address Mr. Landry's issue of "standard" vs "special"
certificates.

Neal,

I guess I made my post because I was looking for supporting or consenting
opinions from the group as to whether I can to a correct conclusion in trying
to interpret the FAR's.

of course I realize each FAA FSDO or MIDO would have their own interpretation
(don't they always)?

Best regards,

John L.

John,

There is NO minimum equipment list in the FARs for an experimental category
aircraft, no interpretation is necessary.

The equipment requirement (and it only applies to other than day VFR) is spelled
out in the Operating Limitations for the aircraft. From my freshly issued
Operating Limitations:

" 8. After completion of Phase 1 flight testing, unless appropriately equipped
for night and/or instrument flight in accordance ?91.205, this aircraft is to be
operated under VFR day only."

So while there is no minimum list, the Operating Limitations placed on the
aircraft at the time of airworthiness certificate issuance dictates the
equipment and instrumentation needed for other than day VFR.

If you are still not convinced, call your MIDO or FSDO and get them to tell you
where to find the boilerplate they use when issuing Operating Limitations. It
is in one of the ACs but I don't remember the exact number.

CW