Many pilots have mistakenly underestimated the potential for Part 103 (Ultralight) balloons. This is the first in a series of articles in which we encourage pilots to design and build these systems.
The Balloon Builders Journal has received a number of inquiries regarding the limits for balloons operated as ultralight vehicles under FAR Part 103. The most common questions are concerned with the maximum allowable weight for the balloon and the limit on the amount of fuel that can be carried.
Many readers are confused because they limit their study to only FAR Part 103. In particular, because an ultralight hot-air balloon carries propane fuel, readers mistakenly consider it a 'powered' rather than an 'unpowered' vehicle.
For a clearer picture as to the FAA interpretation of Part 103, the reader must review an additional document. This document is Advisory Circular 103-7 which is title? The Ultralight Vehicle. While this Advisory Circular is no available through the Government Printing Office, it can be found at most Federal Depository Libraries, and is available for review at your local FAA office.
The Hot-Air Balloon as Ultralight
FAR 103.1 deals with the applicability of vehicles covered under the ultralight rules. Other sections of FAR Part 103 discuss the operational rules. This article will center its discussion on the vehicles.
As seen in the FAR extract, all ultralight vehicles must first meet three conditions? The vehicle must be designed for and operated by a single occupant (§103.1(a)); it must be used for sport and recreational purposes only (§103.1(b)); and it must not have a foreign or domestic airworthiness certificate (§103.1(c)).
These three conditions cause the balloon pilot little concern. It's the next sections, §103.1(d) and §103.1(e)? that cause confusion. These rules differentiate between 'unpowered' and 'powered' ultralights.
A very clear position on this subject is presented in the Advisory Circular 103-7. Review the following excerpts. Clearly a balloon is treated as 'unpowered':
"12.d: Unpowered Vehicles. An unpowered ultralight cannot be
operated under Part 103 if it weighs 155 pounds or more. Balloons and
gliders are unpowered vehicles."
"16.d: Free Balloons are Considered 'Unpowered.' A balloon, for Part 103
eligibility, is considered an unpowered ultralight, regardless of whether
it drops ballast to ascend or uses heated air. The burner on a hot-air
balloon is used to raise the temperature of the air in the envelope
allowing the balloon to rise. This can be compared to the glider's use of
lifting air as a means of ascending. In both cases, no method of horizontal
propulsion is employed."
"16.d: Free Balloons are Considered 'Unpowered.' A balloon, for Part 103 eligibility, is considered an unpowered ultralight, regardless of whether it drops ballast to ascend or uses heated air. The burner on a hot-air balloon is used to raise the temperature of the air in the envelope allowing the balloon to rise. This can be compared to the glider's use of lifting air as a means of ascending. In both cases, no method of horizontal propulsion is employed."
The Weight Limit
Section 16.c(2) states the following with regard to the items included
in the weight limit:
16.c(2)? Free Balloons. The envelope, lines, harnesses, gondola, burner and fuel tanks are included in this determination. Parachutes and all personal operating equipment and harnesses associated with their use are not included. The weight of the fuel, in the case of a hot-air balloon, or any logical amount of removable ballast, when intended for control of buoyancy of a gas balloon, is not included in the weight specified in §103.1(d).
Based on these excerpts the following conclusion may be drawn: To be classified as an ultralight hot-air balloon the vehicle must have an empty weight of less than 155 pounds, excluding fuel and certain specified equipment such as a parachute.
Let's now look at the question of a fuel limitation. Note that the rules define 'powered' and 'unpowered' ultralights as two separate and distinct types of vehicles. Because of the use of the word 'or' at the end of §103.1(d), the '5 U.S. gallon' fuel limit contained in §103.1(e)(2) pertains only to powered ultralights. This interpretation is further supported by the wording in Section 16.c(2) of AC 103-7, as stated above.
We conclude that an ultralight hot-air balloon may carry any amount of fuel, so long as the empty fuel tanks, are included in a total vehicle empty weight of less than 155 pounds.
What about hot-air airships?
Advisory Circular 103-7 provides the following definition of a
"17a 'Powered' Ultralights Eligible For Operation Under Part 103. All ultralights with a means of horizontal propulsion which also meet the provision of §103.1 are eligible; this includes ultralight airships, helicopters, gyrocopters, and airplanes."
Comparing this to excerpt 16.d, above, the FAA's intent becomes clear:
1. If fuel is used to create only lift, and not used to create horizontal propulsion, then that fuel is not included within the '5 U.S. gallon' limit.
2. If the vehicle has a means of horizontal propulsion, then the fuel which generates the propulsion is limited to '5 U.S. gallons'.
From this the following limits to an ultralight airship can be
Like the ultralight balloon, the ultralight airship must be designed for and operated by a single occupant, it must be used for sport and recreational purposes only, and it must not have a foreign or domestic airworthiness certificate.
An ultralight airship must weigh less than 254 pounds empty weight, except for floats and safety devices like a parachute. It also cannot exceed a maximum level flight speed of 55 knots, (which is unlikely to be a limiting factor in a hot air blimp). The stall speed limit of 24 knots should provide no problem as a lighter-than-air craft should be able to sustain flight at 0 knots.
The airship fuel source that provides propulsive power cannot exceed 5 U.S. gallons. If more than 5 gallons of fuel is carried then the fuel used to propel the vehicle in the horizontal direction should be separate from the fuel providing lift.
The ultralight airship may carry any amount of fuel to power the burner that creates lift. However? the empty fuel tanks must be included in the total empty vehicle weight of less than 254 pounds.
I sent a copy of this article to my good friend, balloon builder/pilot, and FAA nice guy Scott Gardiner. I asked Scott to informally review this interpretation and report back to me. Scott chose to review my conclusions with FAA operations staff in Washington D.C. As a result of that review there exists an 'oral agreement' as to the interpretation of Part 103.1, with respect to ultralight balloons and blimps.
That understanding supports the text written above with the following
The FAA places special emphasis on the 'pleasure and sport' aspects of the ultralight rules. They are very sensitive to activities which are commercial in nature or may be perceived as commercial. From that perspective, ultralight balloons or blimps which display advertising banners may be subject to special scrutiny.
Builders who choose to fly ultralights using the interpretation contained in this article are encouraged to keep a copy of this article for reference. If your local FAA official disagrees with this interpretation, ask him or her to contact either of the following for clarification:
Aviation Safety Program Manager
Seattle Flight Standards District Office
John Wentzell, AFS-820
The General Aviation and Commercial Division
This article first appeared in the May-June 95 issue of The Balloon Builders Journal and is reprinted with permission of the author. Editor
This Part prescribes rules governing the operation of ultralight vehicles in the United States. For the purposes of this Part, an ultralight vehicle is a vehicle that:
(a) Is used or intended to be used for manned operation in the air by a single occupant;
(b) Is used or intended to be used for recreation or sport purposes only;
(c) Does not have any U.S. or foreign airworthiness certificate, and,
(d) If unpowered, weights less than 155 pounds, or
(e) If powered:
(1) Weighs less than 254 pounds empty weight, excluding floats and safety devices which are intended for deployment in a potentially catastrophic situation;
(2) Has a fuel capacity not exceeding 5 U.S. gallons;
(3) Is not capable of more than 55 knots calibrated airspeed at full power in level flight; and
(4) Has a power-off stall speed which does not exceed 24 knots calibrated airspeed.