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1) In the US, would it ever be legal to fly a loop in any US-registered airplane or glider that was operating in the "utility" category rather than the "acrobatic" category? (Assuming that no special waiver has been issued by the FAA: the question is not about Bob Hoover's famous Aero Commander routine etc.) Among other things, please consider the possibility that a loop may be listed as an approved maneuver in the "utility" category in the aircraft manual, which may or may not have originated in the US.

2) And here's a closely related, but more specific question, that I'd also like answered: Is it accurate to say that inside loops are generally permitted while flying in the "utility" category in the DG-1000S sailplane in Germany, but not while flying a US-registered DG-1000S in the US in the utility category?"

This FAR seems highly relevant:

§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.

Some context-- note the extensive discussion of "semi-aerobatic" gliders here. I don't know whether said gliders are certified in the "acrobatic" category or not; certainly there are some aerobatic maneuvers that they are not cleared to do.

https://groups.google.com/forum/m/#!topic/rec.aviation.soaring/3UgaY9ydB6o

This link to a US glider club website suggests the answer to the first question is "yes" -- unless someone is just suggesting it's ok to be lax with the regulations-- the statement is made that it is "approved" to loop some gliders -- specifically including the DG-1000S-- when flown at a weight that puts them in the "utility" category, while at a lighter weight the same gliders would be in the "aerobatic" category and would be approved for more maneuvers.

quoting:

Approved Maneuvers in Utility Category

DG-1000: ● G.W. below 1650 lbs ● No water ballast ● Tail ballast used to compensate for rear pilot OK

Approved Maneuvers: ● Spins ● Inside Loop ● Chandelle ● Lazy Eight (Wingover) ● Stall Turn (Hammerhead)

More advanced requires Aerobatic category

(From https://www.flybasa.org/s/basic-aerobatics.pdf )

More information: the English version of the factory-produced flight manual for the German-made DG-1000S glider (may be downloaded here) states the following--

2.6 Approved manoeuvres Category „Utility“: The glider is certified for normal gliding in the "Utility" category. Simple aerobatics are approved but only without waterballast and with the weight of the rear pilot compensated by ballast in the ballast box in the fin see section 6.8.7.

The following aerobatic manoeuvres are approved with all spans:

Spins

Chandelle

Inside loop

Turn

Lazy Eight

Recommended entry speeds see section 4.5.8.1.

The manual then goes on to describe additional maneuvers allowed when flown at a lower weight limit, in the "aerobatic" category:

In addition to the manoeuvres in category „Utility“ the following manoeuvres are approved:

Inverted flight

half flick roll from normal to inverted flight with half loop

half loop and half roll

half flick roll from inverted to normal flight

half roll and half loop

slow roll

This link to an Australian aerobatics association website suggests that in that country, for any given aircraft, the pilot's handbook or cockpit placards will list all the maneuvers allowed in the Utility category, while in the Aerobatic category all standard aerobatic maneuvers are assumed to be permitted unless specifically listed as not allowed in the pilot's handbook or cockpit placards:

http://www.aerobaticsaustralia.com.au/ACC_WP/pilot-briefing/casa-guidelines/

But this link to a related A.S.E. answer suggests the answer to the first question in the US is "no"--

What are the US definition and restrictions on aerobatic flight?

So, please help me sort this out--

If your answer contains any answers to these additional closely related questions, it would be appreciated:

3) What, if any, FARs other than 91.9 are involved in the answer to question (1)?

4) In the US, is the situation in regard to question (1) fundamentally different for gliders than for airplanes for any reason?

5) What if a US-registered aircraft, and its flight manual, predates the establishment of the "utility" and "aerobatic" categories? Is it then up to the pilot's discretion whether to loop it or not in the US?

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Here's what the Cessna 172S POH says. If you attempt any aerobatics outside of this, you are pretty much a test pilot. Nothing here about loops.

UTILITY CATEGORY

SECTION 2

LIMITATIONS This airplane is not designed for purely aerobatic flight. However, in the acquisition of various certificates such as commercial pilot and flight instructor, certain maneuvers are required by the FAA. All of these maneuvers are permitted in this airplane when operated in the utility category.

In the utility category, the rear seat must not be occupied and the baggage compartment must be empty.

UTILITY CATEGORY MANEUVERS AND RECOMMENDED ENTRY SPEED*

Chandelles ................................. 105 Knots

Lazy Eights ................................. 105 Knots

Steep Turns ................................. 95 Knots

Spins ............................... Slow Deceleration

Stalls (Except Whip Stalls) ................ Slow Deceleration

  • Abrupt use of the controls is prohibited above 98 knots. Aerobatics that may impose high loads should not be attempted. The important thing to bear in mind in flight maneuvers is that the airplane is clean in aerodynamic design and will build up speed quickly with the nose down. Proper speed control is an essential requirement for execution of any maneuver, and care should always be exercised to avoid excessive speed which in turn can impose excessive loads. In the execution of all maneuvers, avoid abrupt use of controls.
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  • $\begingroup$ The answer is a useful data point so thanks. The intent of the question is to ask whether there are any cases where it is ok (legal), not to ask whether it is legal in all cases; hope you don't feel latest edit (use of word "any") invalidates your answer, if so guess I could roll back. $\endgroup$ – quiet flyer Jul 14 at 19:40
  • $\begingroup$ In an emergency, the pilot in command can do whatever is needed to resolve the emergency. Diving down to put out an engine would build up speed, then when the fire is out, you need to pull out of the dive & land. Would you need to perform a loop for that? Doubtful. I can't think of any reason why a loop would need to be performed. $\endgroup$ – CrossRoads Jul 14 at 22:14
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    $\begingroup$ The intent is to ask if there are cases where it is fine ( compliant with US regs) to take off with the intention of performing loops while operating in utility category- perhaps because loops are listed as allowed in utility category in aircraft manual or on placards. Not really intending to ask about emergencies. $\endgroup$ – quiet flyer Jul 14 at 22:31
  • $\begingroup$ In "The Handbook of Glider Aerobatics", dwnldble here s3-eu-west-1.amazonaws.com/bga-sg-archive/Books/…, table 2 on page 31 lists 9 differnt glidrs incldng K13/K10/K8, K6e, K6cr, Pirat, St'd Jantar, ASW19 and GrobG102 tht are suitable for loops but NOT for rolling maneuvers. Whether these gliders -- the newer ones that don't predate the whole "category" system-- are in the "utility" or "aerobatic" category when flown at their most favorable CG position and loading, I have no idea. $\endgroup$ – quiet flyer Jul 16 at 19:32
  • $\begingroup$ Likewise I have no idea whether it would be legal to loop all these 9 gliders types in the US in US-registered aircraft. $\endgroup$ – quiet flyer Jul 16 at 19:33
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As noted in the question, the flight manual for the German-made DG-1000S sailplane specifically states that loops are permitted in the "utility" category. More advanced maneuvers are permitted at a lighter loading, when the glider is in the "utility" category.

In "The Handbook of Glider Aerobatics", downloadable here , table 2 on page 31 lists 9 different gliders ( K13/K10/K8, K6e, K6cr, Pirat, Standard Jantar, ASW19 and Grob G102 (non-acro)) (none of which are or were manufactured in the US) that are cleared for loops but not rolling maneuvers. While some of these aircraft may predate the whole "category" system, it seems inconceivable that any are actually in the "aerobatic" category at any loading or CG position. For example, I have looked at the flight manual for the Grob 102 Astir CS downloadable here, which does state that loops are allowed, and there is no long list of prohibited maneuvers, as would surely need to be the case if the aircraft were actually in the "aerobatic" category but not allowed to fly any rolling maneuvers. (The flight manual for the Grob 102 "Astir" actually makes no reference whatsoever to "category", be it "normal", "utility", "aerobatic", or other.)

I strongly suspect that any maneuver specifically listed by an aircraft's flight manual as permitted in the "utility" category, is in fact legal to fly in the US, at the "utility" loading, in a US-registered example of that aircraft. Clearly in at least one instance (the DG-1000S sailplane) this would include inside loops.

I also strongly suspect that any maneuver listed as permitted in the flight manual of an aircraft that predates the whole "category" system, is in fact legal to fly in the US in a US-registered example of that aircraft, even if not registered in the "aerobatic" category.

I'm aware of no FAR that explicitly states that a US-registered aircraft must be being listed and flown in the "aerobatic" category in order to be looped, even if the flight manual permits loops to be flown in other categories, or even if the flight manual predates the "category" system.

So the answers to the questions appear to be:

1) In the US, would it ever be legal to fly a loop in any US-registered airplane or glider that was operating in the "utility" category rather than the "acrobatic" category?

Yes, if the loop is listed as an approved maneuver in the utility category, as is sometimes the case.

2) And here's a closely related, but more specific question, that I'd also like answered: Is it accurate to say that inside loops are generally permitted while flying in the "utility" category in the DG-1000S sailplane in Germany, but not while flying a US-registered DG-1000S in the US in the utility category?"

No

3) What, if any, FARs other than 91.9 are involved in the answer to question (1)?

Unknown at this time

4) In the US, is the situation in regard to question (1) fundamentally different for gliders than for airplanes for any reason?

Not in a regulatory sense. In a practical sense, the difference is that gliders due to their long wingspans typically have a rather low roll rate. To design a glider that can roll well requires a big sacrifice of soaring performance. This is not true of looping, especially in the case of a glider that is designed to tolerate the load of heavy water ballast, but will only be looped without water ballast. So it's not surprising that we see many gliders that are cleared for loops but not rolls. It's more logical to accommodate this by adding loops to the list of maneuvers that are allowed in the utility category, than to say that the glider is in the aerobatic category but with a very long list of prohibited maneuvers. (Note also that a rolling capability really is required to safely exit other maneuvers such as sustained inverted flight--especially after a piloting error resulting in some excess buildup of airspeed-- which might otherwise be perfectly within the capability of many gliders.) Conversely, with a typical light plane, it is easier to roll the plane then to loop the plane, so I'm not sure why we never see aileron rolls added to the list of allowed maneuvers in the utility category for some airplanes.

5) What if a US-registered aircraft, and its flight manual, predates the establishment of the "utility" and "aerobatic" categories? Is it then up to the pilot's discretion whether to loop it or not in the US?

The complete answer is unclear but any maneuvers specifically listed as permitted in the flight manual would likely to be allowed to be performed in the US in a US-registered example of that aircraft.

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  • $\begingroup$ This answer could be improved by finding more authoritative sources. Or another better answer could be posted that relied on more authoritative sources. $\endgroup$ – quiet flyer Jul 16 at 20:18
  • $\begingroup$ In particular the issue of the fact that the flight manuals produced above were not for us-manufactured aircraft, so would maneuvers listed in the "utility" category still be legal to be flown in the US for US-registered examples of those aircraft, has not been completely settled. But I see no FAR that says "an aircraft must be in the aerobatic category in order to perform a loop." $\endgroup$ – quiet flyer Jul 16 at 20:27

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