Can you turn a constant speed prop into a fixed pitch?

[fatsportpilot]

If a plane that is otherwise an LSA comes with a constant speed prop can I (or a mechanic) just disable the governor so it becomes ground adjustable or fixed pitch or would I need to buy a new prop?

Or is it once a "constant speed prop always a constant speed prop" in law?

[drseti]

In a more general case, any aircraft that has ever been operated outside of the LSA restrictions can never subsequently be operated as an LSA.

The classic example of this rule is the Ercoupe 415C. The 1946 C model originally met all of what later became the LSA rules. It had a maximum gross weight of 1260 pounds. Decades back, there was an STC enabling max gross to be increased to 1400 pounds. Since LSA didn't yet exist, most owners bought that STC (there was no good reason not to).

Then in 2004, the LSA rule came out, and a whole bunch of 415Cs appeared on Trade-a-Plane, advertised as LSAs. Most were not legal, because they had acquired that STC. And ripping up the STC didn't cut it, because the FAA aircraft registry showed that the 1400 pound STC had been issued.

Right now, even adjusting for inflation, a truly LSA compliant Ercoupe 415C has more than doubled in value from its pre-2004 price, because legal LSA 'Coupes are so rare.

[fatsportpilot]

So if a plane that is otherwise LSA has a constant speed prop then I could not buy it and even replace the prop to operate it under sport pilot rules? What if it was manufactured and the constant speed prop installed in another country and it was fitted with a fixed before being shipped to the US?

[drseti]

From the FAA website:

LSA manufactured outside the United States may be issued special airworthiness certificates when proof is provided to show:
Compliance to the airworthiness regulations, 14 CFR 21.190,
The LSA has been manufactured in a country with which the U.S. has a Bilateral Airworthiness Agreement or BASA with associated IPA or equivalent airworthiness agreement, and
The aircraft is eligible for an airworthiness certificate or similar certification in its country of manufacture.

Now, FAR 21.190(b)(2) says:

The aircraft must not have been previously issued a standard, primary, restricted, limited, or provisional airworthiness certificate, or an equivalent airworthiness certificate issued by a foreign civil aviation authority.

So I would say that precludes what you proposed.

[drseti]

From FAR 1.1 (emphasis added):

Definition. As defined in FAR 1.1, a light-sport aircraft is an aircraft other than a helicopter or powered-lift that since its original certification has continued to meet the following:

- A maximum takeoff weight of not more than 660 pounds (300 kilograms) for lighter-than-air aircraft; 1,320 pounds (600 kilograms) for aircraft not intended for operation on water; or 1,430 pounds (650 kilograms) for aircraft intended for operation on water.

- A maximum airspeed in level flight with maximum continuous power (VH) of not more than 120 knots calibrated airspeed under standard atmospheric conditions at sea level.

- A maximum never-exceed speed (VNE) of not more than 120 knots calibrated airspeed for a glider.

- A maximum stalling speed or minimum steady flight speed without the use of lift-enhancing devices (VS1) of not more than 45 knots calibrated airspeed at the aircraft’s maximum certificated takeoff weight and most critical CG.

- A maximum seating capacity of no more than two persons, including the pilot.

- A single, reciprocating engine, if powered.

- A fixed or ground-adjustable propeller, if a powered aircraft other than a powered glider.

- A fixed or auto-feathering propeller system, if a powered glider.

- A fixed-pitch, semi-rigid, teetering, two-blade rotor system, if a gyroplane.

- A nonpressurized cabin, if equipped with a cabin.

- Fixed landing gear, except for an aircraft intended for operation on water or a glider.

- Fixed or repositionable landing gear, or a hull, for an aircraft intended for operation on water.

- Fixed or retractable landing gear for a glider.

[3Dreaming]

So if a plane that is otherwise LSA has a constant speed prop then I could not buy it and even replace the prop to operate it under sport pilot rules? What if it was manufactured and the constant speed prop installed in another country and it was fitted with a fixed before being shipped to the US?

If it was a new airplane, then maybe. The solution may be problematic. How would you get an airworthiness certificate? If the airplane is manufactured in a foreign country with a constant speed propeller it may not be manufactured to ASTM standards, so then it can't be a SLSA. It can't be a ELSA if there isn't a ASTM compliant version to copy. That makes getting an airworthiness certificate an issue.

[chicagorandy]

"The classic example of this rule is the Ercoupe 415C. The 1946 C model originally met all of what later became the LSA rules. It had a maximum gross weight of 1260 pounds. Decades back, there was an STC enabling max gross to be increased to 1400 pounds. Since LSA didn't yet exist, most owners bought that STC (there was no good reason not to)."

I reckon that gives 415-C owners of planes that ARE compliant some comfort know that being unintentionally 140# over original gross is "safe"....though still completely against the rules? 140lbs is a lot of fuel.

[Warmi]

"The classic example of this rule is the Ercoupe 415C. The 1946 C model originally met all of what later became the LSA rules. It had a maximum gross weight of 1260 pounds. Decades back, there was an STC enabling max gross to be increased to 1400 pounds. Since LSA didn't yet exist, most owners bought that STC (there was no good reason not to)."

I reckon that gives 415-C owners of planes that ARE compliant some comfort know that being unintentionally 140# over original gross is "safe"....though still completely against the rules? 140lbs is a lot of fuel.

I believe you gonna get virtually spanked on this forum for even suggesting this

[drseti]

I reckon that gives 415-C owners of planes that ARE compliant some comfort know that being unintentionally 140# over original gross is "safe"

Remember that stall speed increases with weight. Unlike non-LSAs, 'Coupes flown by Sport Pilots are restricted to a clean stall speed limit of 45 knots calibrated. I'm pretty sure that extra 140# would put you over that limit. (And for those who think an Ercoupe can't stall, wrong! It is merely stall resistent.) In the case of the Sport Pilot eligible 415Cs that have been increased to 1320#, be aware that the STC includes modifying the elevator range of motion to limit angle of attack, thus solving the stall speed issue.

[fatsportpilot]

"The classic example of this rule is the Ercoupe 415C. The 1946 C model originally met all of what later became the LSA rules. It had a maximum gross weight of 1260 pounds. Decades back, there was an STC enabling max gross to be increased to 1400 pounds. Since LSA didn't yet exist, most owners bought that STC (there was no good reason not to)."

I reckon that gives 415-C owners of planes that ARE compliant some comfort know that being unintentionally 140# over original gross is "safe"....though still completely against the rules? 140lbs is a lot of fuel.

I believe you gonna get virtually spanked on this forum for even suggesting this

What's wrong with feeling comfortable with a plane that has extra safety margin? I like a plane that I know will not kill me if I over gross accidentally or collapse the nose gear if I bounce it. If you do go over gross then you would have to know that 1. it is not legal and 2. your stall speed would change.

For example I feel better in a plane that is certified for tail slides because I know there is no chance for damage to the control surfaces in heavy turbulence even if I know I will never perform a tail slide in it. I know that even a non aerobatic plane would be safe but that extra margin of safety is nice.

[drseti]

What's wrong with feeling comfortable with a plane that has extra safety margin?

Absolutely nothing. What is wrong is thinking that an extra safety margin translates to an extra operating margin. For example, it is wrong for the marketing manager of a certain European LSA to respond to complaints about their product's marginal useful load by saying, "well, in Europe this plane is rated at 1400 pounds, so it can handle it."

Wink wink, nudge nudge.

[fatsportpilot]

I agree with that. Even if it would be aerodynamically safe it makes us look bad to break the rules.

I think I know what plane you mean. That's the kind I fly (without the vortex generators) and I appreciate that it has such a good safety margin.

[chicagorandy]

"I believe you gonna get virtually spanked on this forum for even suggesting this "

Well then "Beat me, whip me and make me feel cheap" - LOL

71 yrs years of 'living' has not made me any smarter than I was, but it sure has providing some powerful fierce perspective on life.

[Warmi]

I am not the one doing any spanking here

My approach has always been - don't look at what is defined as legal but rather what is right and safe.
Very often both converge on the same underlying concept but not always ...

[foresterpoole]

OK maybe I am behind the times, but aren't there LSA's in development with the 912iS that actually use a governor to vary the pitch and single throttle control? I'm not saying they are currently LSA compliant, but I know it has been discussed and is being widely touted as safe and efficient....