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Posting Vx and Vy speeds

tracy

Well Known Member
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Where should these speeds be published for certain experimental aircraft, In the operational limitations, or in airframe manual?
 
Check your OPLIMs. When mine were issued they included this statement “Compliance with 14 CFR § 91.319(b) must be recorded in the aircraft records with the following, or a similarly worded, statement: “I certify that the prescribed flight test hours have been completed and the aircraft is controllable throughout its normal range of speeds and throughout all maneuvers to be executed, has no hazardous characteristics or design features, and is safe for operation. The following aircraft operating data has been demonstrated during the flight testing: speeds Vso ______, Vx ______, and Vy ______, and the weight ______, and CG location ______ at which they were obtained.”

So I’ve got an entry in my airframe log with this paragraph filled in. There’s no requirement for an E-AB aircraft to actually have a POH or AFM. However I believe it’s prudent to have one, and I do and it’s modeled after a Cessna POH and lists all the pertinent V speeds.
 
The builder has to find those numbers by flight testing in Phase I and document them. No two experimentals are built exactly alike, so every plane is different, and your V-speeds may be different than anyone elses - so you have to find yours by testing.
 
Here's an extract from my AFM (POH) if it helps:

Airspeeds for normal operations are listed below. Unless otherwise noted, all airspeeds are based on a maximum takeoff weight of 816 kg (1800 lbs) at sea level under ISA standard day conditions.

Takeoff (VR) (1.1 * Vs) 55 KIAS
Best Angle (VX) 70 KIAS
Best Rate (VY) 97 KIAS
Best Glide 90 KIAS
Maximum Maneuvering Speed (VA) 123 KIAS
Maximum Normal Operating Speed (VNO) 168 KIAS
Never Exceeded Speed (VNE) 200 KTAS


Vs, Vx, Vy, and Best Glide were determined by flight testing. Other numbers came from the factory.
 
FAR 91.9 (b) (2) ?

No, it is not required.

91.9 Civil aircraft flight manual, marking, and placard requirements.

(a) Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry.

(b) No person may operate a U.S.-registered civil aircraft -

(1) For which an Airplane or Rotorcraft Flight Manual is required by § 21.5 of this chapter unless there is available in the aircraft a current, approved Airplane or Rotorcraft Flight Manual or the manual provided for in § 121.141(b); and

(2) For which an Airplane or Rotorcraft Flight Manual is not required by § 21.5 of this chapter, unless there is available in the aircraft a current approved Airplane or Rotorcraft Flight Manual, approved manual material, markings, and placards, or any combination thereof.


There is no process in place to approve a manual for an E-AB aircraft, so the "combination of" markings and placards is what meets the requirement.
That is why instrumentation has to be appropriately marked with operating ranges, etc.
 
NOT REQUIRED

A POH is not required in an experimental aircraft, as others have posted. The operating limitations issued at the A/W inspection comply with the rules.

That said, a nice POH is a finishing touch on a remarkable project...
 
Best fit for Vx/Vy question

I love these discussions as they bear out the nature and detail of our regs.

Where would marking or placarding of Vx/Vy ( OP question ) fall? Remember it must be in the airplane.

Just to tease that thought: Many folks have a p.o.h. and while it isn't an Approved P.O.H., it is still marked up with limitations and performance numbers and carried in the airplane.
 
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Well...

"...Where would marking or placarding of Vx/Vy ( OP question ) fall? Remember it must be in the airplane..."

Well, most EFIS systems show those numbers on the speed tape.

For those with steam gauges, a radial mark pn the airspeed indicator is a likely spot.

Of course they should be listed in the ops limitations which are required to be carried in the plane.
 
The thing to remember folks, is that you’re not even required to have an airspeed indicator…… ;)
 
"A manufacturers POH still must be onboard an experimental aircraft, even if it is written by the builder"

Is he right? Does it matter?

The Inspector at the FSDO offered this article to help understand what the FAA may come looking for:

https://www.eaa.org/eaa/aircraft-bu...-and-cabin-interior/markings-placards-numbers

My 2 cents is he’s not. There are tons of examples of FSDO inspectors making up things as they go along even when confronted with contradictory FAR evidence. That said sometimes it’s best to go along, get the sign off, then rejoin the world of common sense.

So once again, a POH is not required, but most agree that’s it’s a really good idea. All 91.9 says is you have to comply with the specified OPLIMs, not have a POH/AFM, although for some aircraft that’s where they are located, but not for E-AB. That’s where the “or otherwise prescribed” language comes into play. Furthermore the rest of the paragraph which is based upon 21.5 which applies to type certificated aircraft which doesn’t apply to E-ABs. For E-AB aircraft the OPLIMs are annotated as part of the AWC and must be maintained as such.
 
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Digging deeper...

"...unless there is available in the aircraft a current approved Airplane or Rotorcraft Flight Manual, approved manual material, markings, and placards, or any combination thereof.

The highlighted section says it all; as long as you have "markings and/or placards" you have complied with the rule, and a POH is NOT required.
 
What if the FAA rep is 'wrong'

I am sure a sampling of FSDOs on this topic will yield a sampling of answers. Like I mentioned before: 'does that matter' to us who just want to operate our aircraft safely and not spend a lot of time arguing the FAA's rules with a representative of the FAA?

If we get checked by MY local inspection office and we do not have a p.o.h. we can certainly try to stand on the letter of 91.9 claiming 'any combination' of placards and markings is sufficient. It's a chump's challenge for them to come back with: 'show me your placard or marking for....' You may keep up for a while, but they'll win that game whether you agree or not. You'll be left blowing spit bubbles in front of an inspector who has gotten his/her back up.

You may eventually win that war if that kind of thing is something you want to spend time doing, but you'll probably lose that particular battle.

Assuming you have an airspeed indicator and have determined Vx/Vy (OP's intent) where should you put that? Best all around answer is a p.o.h. even if it isn't a P.O.H.

For example: Most of us know the acronym ARROW for required docs carried even if it is a little out of date regarding radio licenses. The W is for Weight and Balance documentation. Try finding where the carriage of weight and balance numbers is specifically required by FARs for simple part 91 operations. The PHAK (FAA-H-8083-25B) while non-binding calls out "there are no specified requirements for a pilot operating under 14 CFR part 91 to conduct weight and balance calculations" But that won't stop a world of nuisance if some ramp checker has got that bug in their bonnet and you don't have access to those numbers.

If my local FSDO claims I need to wear green socks on St Patrick's day then I'll probably consider it just to make my life easier.

Today at least one FAA rep has gone on record that they will need to see a p.o.h. in EA aircraft. From a Safety perspective (and we hope that is their motivation) what can be criticized about the expectation for each of us to go through the rigor and exercise of writing our own p.o.h? To carry that example forward: Is there a good argument for NOT carrying the numbers to be able to do a weight and balance calculation prior to each flight?
 
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Well you asked for our opinions which we provided with rationale to support them. However, our opinions don’t mean squat. In the end each one of us has to make their own interpretations and move out accordingly.
 
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Assuming you have an airspeed indicator and have determined Vx/Vy (OP's intent) where should you put that?

In the Ops Limits, the section with the blanks for Vy and Vx, which have to be on-board the aircraft? I did, although there's also an entry in the aircraft logbook (but that's no on-board).

A: In the EFIS, so it's displayed on the tapes, or on the steam gauge ASI just like those antiques that don't have glass.
 
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