18220 Federal Register / Vol. 61, No. 80 / Wednesday, April 24, 1996 / Rules and Regulations

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 31

[Docket No. 27543; Amendment No. 31–7]

RIN 2120–AE87

Airworthiness Standards; Manned Free

Balloon Burner Testing

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This final rule amends the

certification test requirements for

burners used on manned free balloons.

The current test requirements do not

test the burner’s most critical operating

conditions. This amendment will

increase the current level of safety by

requiring more realistic tests and cut the

fuel costs to balloon manufacturers

seeking certification.

EFFECTIVE DATE: May 24, 1996.

FOR FURTHER INFORMATION CONTACT:

J. Lowell Foster, Standards Office (ACE–

110), Small Airplane Directorate,

Aircraft Certification Service, Federal

Aviation Administration, 601 East 12th

Street, Kansas City, Missouri 64106;

telephone (816) 426–5688.

SUPPLEMENTARY INFORMATION:

Background

Statement of the Problem

The current burner certification

requirement resembles the testing

requirement for airplane engines.

Airplane engines are operated

continuously at high percentage powers,

while balloon burners are operated on

an intermittent basis to maintain level

or buoyant flight. The burner

requirement calls for maximum fuel

flow burning over the majority of the

test time. This requirement does not

reflect the fact that a burner is

continually turned on and off every few

seconds or that a minimum heat output

condition is much more critical than a

maximum heat output condition. The

challenging test conditions for a burner

are short blasts to maximize the thermal

shock and operation on vapor, which

can result in the burner coils glowing

red.

Since certification testing should

simulate flight conditions and the

critical concern is not the duration of

operation but the number of mechanical

and thermal cycles, this final rule would

change the balloon burner requirements

to include testing of mechanical and

thermal cycles, and testing of operation

on vapor. As a result, the burners would

be tested over a 40-hour period instead

of 50-hour period.

The Proposal

This amendment is based on Notice of

Proposed Rulemaking (NPRM), Notice

No. 93–16, which was published on

December 7, 1993 (58 FR 64450). The

Federal Aviation Administration (FAA)

proposed to amend § 31.47(d) to remove

30 test hours at maximum heat output

and require, instead, additional testing

that focuses on critical functions

experienced during flight. More

specifically, the FAA proposed changes

in the balloon burner requirements to

include testing of mechanical and

thermal cycles, and testing of operation

on vapor. The burners would be tested

over a 40-hour period instead of 50

hours. The testing would be for

specified periods at maximum,

intermediate, and minimum fuel

pressures and would include burn times

of 3 to 10 seconds per minute instead

of continuous burning. The term

‘‘intermediate fuel pressure’’ would be

defined as 40 to 60 percent of the range

between the maximum and minimum

applicable fuel pressures in order to

provide for testing the burners near the

mid-point of their ranges of operation.

The FAA also proposed to change the

word ‘‘heater’’ to ‘‘burner’’ in § 31.47.

The industry universally uses the term

‘‘burner,’’ and this change reflects

accepted industry terminology.

Discussion of Comments

Comments to the NPRM were

requested with a closing date of

February 7, 1994. All comments

received have been considered in

adopting this amendment.

The FAA received comments from

Transport Canada, which supports the

proposal, and from two prominent

balloon manufacturers. One

manufacturer agrees in general with the

proposals, but offers three suggestions

that are outside the scope of this

proposal. The other recommends that

the FAA adopt the British standard for

§ 31.47. The FAA will address these

comments in the order they were

submitted.

Concerning proposed § 31.47(d)(1)(i),

the commenter states, ‘‘Mechanically

cycling the main blast valve not only

demonstrates wear but provides the

hydraulic shock necessary to adequately

test the entire fuel system. However, the

on/off cycle for each system should be

different because of its thermal mass.

For example, our burner has two cast

alloy base plates and thin wall Inconel

vaporizing coils. Some burners have

very heavy coils and only pipe-type

tubing to and from the blast valve. A

pre-test should be done to determine the

widest possible temperature swing of

any of the elements that will be ‘in the

fire’ and subject to heat-stress failures.

This will provide the on/off time.’’ The

commenter proposes that the rule be

reworded to include, ‘‘a burn time for

each one minute cycle which has been

previously established [by a pre-test to

determine the widest possible

temperature change of any of the

elements, as discussed above] to provide

the maximum thermal shock to

temperature effected [sic] elements, but

in no case less then four seconds.’’

The FAA recognizes the merit of this

comment concerning a burn time that

would provide the maximum thermal

shock to temperature-affected elements.

The intent of proposed § 31.47(d)(1)(i)

was to allow each applicant to predetermine a burn time for the particular

system undergoing certification testing

such that the thermal cycle used in the

testing would provide approximately

the maximum difference between the

coolest and hottest temperatures the

burner coils and affected hardware

would experience in service. Although

the preamble to Notice No. 93–16 did

not refer specifically to testing that

would achieve the maximum

temperature differential, it did

emphasize the need to simulate actual

flight conditions, during which the

burner is subjected to thermal shock

from its intermittent operation.

Referring to the extreme temperature

change that occurs when vaporized fuel

cools the entire assembly followed by

flames engulfing the vaporizing coils,

the notice stated that the critical

concern was the number of mechanical

and thermal cycles.

In order to achieve the necessary

thermal shock, the FAA proposed a

burn time range of from three to ten

seconds for each one minute cycle of the

test. From within that time range, an

applicant, through pre-certification

testing, would determine the burn time

that would maximize the temperature

differential experienced by the system’s

temperature-affected elements.

Although Notice No. 93–16 did not

explain how the FAA arrived at the

proposed 3 to 10 second range for the

burn time, that range was proposed

because the FAA had learned from

previous certification testing that this

time range is reasonable and reflects the

range of burn times within a one-minute

cycle from which the maximum

temperature differential may be

obtained.

Nevertheless, because, as pointed out

by the commenter, the requirement as

proposed did not make clear that the

purpose of the 3 to 10 seconds of burn
Federal Register / Vol. 61, No. 80 / Wednesday, April 24, 1996 / Rules and Regulations 18221

time was to ensure that the burner being

tested is subjected to the maximum

thermal shock, the regulatory text of

§ 31.47(d)(1)(i) is being clarified by

adding a sentence to state explicitly that

requirement. The FAA believes that the

added requirement to assure that the

maximum thermal shock is achieved

during testing reflects the intent of the

proposed amendment and is necessary

to increase safety by more closely

simulating flight conditions. Although

the commenter suggested a minimum

burn time of four seconds, based on the

FAA’s prior certification experience the

burn time requirement for each minute

cycle of testing remains at 3 to 10

seconds as proposed.

Referring to § 31.47(d)(1)(iv), the

commenter states, ‘‘A pilot who

consistently uses incorrect fuel

management techniques may get into

situations where he subjects the burner

to the stress of running on vapor. The

degradation of some parts is cumulative

and it would be good to be assured that

vaporizing coils, for example, would not

fracture without warning in flight.’’ To

achieve this goal, the commenter

recommends the FAA double the time

for this test.

The FAA has determined that testing

for a total of 15 minutes, as specified in

the proposal, should provide confidence

that the burner will not suffer from

undue thermal stresses while not

imposing an unwarranted burden on the

manufacturer. Manufacturers have told

the FAA that their balloons would not

fly long on vapors before the pilot

would notice the balloon descending.

The manufacturers state that the heat

output from a burner operating on vapor

is not enough for the balloon to hold

altitude. Even with vapor burning

constantly, the balloon will develop an

increasing rate of descent. For this

reason, several manufacturers suggested

that 30 minutes was extreme and would

constitute a burden to them. The FAA

could not justify, based on any adverse

service history, requiring a test of more

than the originally proposed 15 minutes

total time of burner operation on vapor;

therefore, the § 31.47(d)(1)(iv) will

retain the 15 minute standard as

proposed.

The same commenter offers the

following suggested rewrite for

§ 31.47(d)(1)(v): ‘‘Fifteen hours of

normal flight operation during which

backup burner and pilot lights must be

extinguished and relighted at least twice

in each flight hour.’’ The commenter

justifies this recommended change by

explaining that backup burner and pilot

lights may be easy to relight on the

ground when the burner is mounted in

a test fixture but may be difficult to

relight when it is in position during

flight.

The FAA acknowledges the merits of

this comment concerning backup

burners and notes that currently

§ 31.47(e) does not specify testing the

backup burner. However, the FAA may

not impose an additional burden on the

public without offering the public an

opportunity to comment on the

proposed requirements. This comment

addresses a matter that is beyond the

scope of the proposed rule change;

therefore, it can be considered only for

future rulemaking projects. Section

31.47(d)(1)(v) is adopted as proposed.

The commenter recommends

rewording the proposal for § 31.47(d)(2)

to read as follows: ‘‘The test program for

the secondary or backup operations of

the burner must include two hours of

operation of the backup burner with a

continuous cycle time of five minutes

on and five minutes off. Test must

include extinguishing and relighting

this burner, without the use of the pilot

light system, at least one time per 30

minutes of testing, while under a

crosswind airflow, the speed of which

must be equal to the highest

demonstrated maximum sink rate for

the balloon systems for which approval

is being sought.’’ The commenter’s

explanation follows:

‘‘The use of the backup burner in

flight may include operation for up to

three or four minutes at a time. During

several certification flights, we were

required to use only the backup for

some flight maneuvers. For example, on

several occasions we did an entire

recovery from Maximum Sink Rate

Descent and on another we did almost

an entire flight using the backup burner

alone.’’

‘‘It is important to do this test with

some airflow to simulate conditions in

flight should the burner have to be used

during a high speed descent. Each

balloon flies at a different rate because

of the drag coefficient/gross weight,

hence the air velocity requirement. In

our testing we use 1300 fpm as a

descent rate maximum and if we exceed

it in our certification flights we reduce

allowable Max Gross System Weight.

This figure appears in the

LIMITATIONS and PERFORMANCE

section of the Aircraft Flight Manual.’’

‘‘A condition may occur in flight

where the backup burner is metered

down to a low flame and is used as a

pilot light system. It is important that it

be demonstrated to light without the use

of pilots [lights].’’

Again, the FAA recognizes the merit

of this comment concerning backup

burner flameouts and relights. Because

this comment addresses a matter that is

beyond the scope of the proposed rule

change, it can be considered only for

future rulemaking projects. Accordingly,

§ 31.47(d)(2) is adopted as proposed.

The commenter recommends adding

new paragraphs (3) and (4) to § 31.47(d).

The recommendation for a new

§ 31.47(d)(3) is to require two hours of

operation of the pilot light system while

under a crosswind airflow with the

wind speed equal to the highest

demonstrated maximum sink rate. The

test would induce extinguishing and

relighting the pilot light at least one

time per 10 minutes of testing. This test

would include testing a piezo-electric

element or other electrical means of

igniting the pilot lights. Again, the

commenter’s reasoning is that backup

burner and pilot lights may be easy to

relight on the ground when the burner

is mounted in a test fixture but may be

difficult to relight when in position

during flight. Also, the commenter

believes that the piezo-electric igniters

are not as reliable in airflow as devices

currently used.

This comment is also beyond the

scope of the proposed rule change and

can be considered only for future

rulemaking projects.

The recommendation for a new

§ 31.47(d)(4) concerns a post-test

teardown of the burner. The commenter

proposes adding the following

requirement: ‘‘A teardown of the burner

should be done to reveal any

abnormalities.’’ Current § 31.47(f)

requires that each element of the burner

system be serviceable at the end of the

test. The FAA agrees with the

commenter that a teardown inspection

at the end of testing is an acceptable

procedure and a means of

demonstrating compliance. However, a

teardown inspection is not an

airworthiness safety standard. The term

‘‘serviceable,’’ as used in aviation,

defines a standard for airworthiness

based on certification testing of the

burner and its components.

The second commenter states that if

the goal of international harmonization

is to be approached, the FAA should

take into account the British, German,

and French codes in proposing changes

to 14 CFR part 31. The commenter also

notes that a number of balloon

manufacturers and representatives of

European regulatory authorities met at

London Heathrow Airport in March

1992 to consider the member nations’

airworthiness requirements for balloons,

and to make recommendations for a

future JAR 31. The commenter includes

the British Civil Airworthiness

Requirements (BCAR) wording that was

recommended for JAR 31.47. BCAR

§ 31.47(d) reads as follows:
18222 Federal Register / Vol. 61, No. 80 / Wednesday, April 24, 1996 / Rules and Regulations

The heater system (including the burner

unit, controls, fuel lines, fuel cells,

regulators, control valves, and other related

elements) must be substantiated by an

endurance test designed to reflect the

limiting conditions likely to be encountered

in service, both in kind and duration. The

endurance test proposed by the

manufacturers must be approved by the

certification authority.

Though the commenter expresses the

view that the version of § 31.47(d)

proposed in No. 93–16 is better than the

existing version, the commenter,

nevertheless, asserts that the proposed

requirement is over-specified and will

soon be rendered obsolete by technical

change. The commenter further states

that the proposals leaves out some

important points, but the commenter

did not identify them.

To adopt the British testing

requirement would be beyond the scope

of the NPRM. The FAA does recognize

the importance of harmonization and is

currently expending extensive resources

to harmonize the Federal Aviation

Regulations with the European Joint

Aviation requirement (JAR). Though the

requirements in BCAR § 31.47(d) may

accommodate new technology more

readily than those proposed in Notice

93–16, the British rule requires the

manufacturer to develop an endurance

test and have it approved by the

certification authority even for current

technology. The proposed amendment

of § 31.47(d) provides a specific

minimum requirement for all burners to

meet. If changing technology were to

render the proposed requirements

obsolete for a new burner, the FAA may

apply ‘‘special conditions’’ for new and

novel technology (14 CFR 21.16).

Accordingly, the rule is adopted as

proposed.

International Compatibility

The agency has reviewed

corresponding International Civil

Aviation Organization international

standards and recommended practices

and Joint Aviation Authorities

requirements and has identified no

differences in these amendments and

the foreign regulations.

Regulatory Evaluation Summary

Proposed changes to Federal

regulations must undergo several

economic analyses. First, Executive

Order 12866 directs that each Federal

agency shall propose or adopt a

regulation only upon a reasoned

determination that the benefits of the

intended regulation justify its costs.

Second, the Regulatory Flexibility Act

of 1980 requires agencies to analyze the

economic effect of regulatory changes

on small entities. Third, the Office of

Management and Budget directs

agencies to assess the effects of

regulatory changes on international

trade. In conducting these analyses, the

FAA has determined that this rule: (1)

will generate benefits that justify its

costs; (2) is not a ‘‘significant regulatory

action’’ as defined in the Executive

Order and is not ‘‘significant’’ as

defined in DOT’s Regulatory Policies

and Procedures; (3) will not have a

significant economic impact on a

substantial number of small entities;

and (4) will not constitute a barrier to

international trade. These analyses,

available in the docket, are summarized

below.

Benefits and Costs

The rule will enhance safety by

targeting critical functions and

conditions experienced in actual flight

and will significantly reduce

certification testing costs. The current

requirements call for a total of at least

50 hours of testing, which typically

consumes about 7,000 gallons of fuel

per type certification. The new

requirements, in contrast, are expected

to consume about 350 gallons of fuel

because the burners will be tested over

a total of 40 hours instead of 50 hours

and be tested about 3 to 10 seconds per

minute instead of the full 60 seconds.

Applying a price of $1.20 per gallon of

propane, the revised requirements are

expected to yield almost $7,800 in net

cost savings per type certification.

Accordingly, the FAA finds the rule to

be cost-beneficial.

Regulatory Flexibility Determination

The Regulatory Flexibility Act (RFA)

of 1980 was enacted by Congress to

ensure that small entities are not

unnecessarily or disproportionately

burdened by Government regulations.

The RFA requires a Regulatory

Flexibility Analysis if a rule is expected

to have a ‘‘significant (positive or

negative) economic impact on a

substantial number of small entities.’’

Based on the standards and thresholds

specified in FAA Order 2100.14A,

Regulatory Flexibility Criteria and

Guidance, the FAA has determined that

the rule will not have a significant

economic impact on a substantial

number of small entities.

International Trade Impact Assessment

The rule will have little or no effect

on the sale of U.S. balloons in foreign

markets and the sale of foreign balloons

into the United States.

Federalism Implications

The regulations herein will not have

substantial direct effects on the States,

on the relationship between the national

government and the States, or on the

distribution of power and

responsibilities among the various

levels of government. Therefore, in

accordance with Executive Order 12866,

it is determined that this regulation will

not have sufficient federalism

implications to warrant the preparation

of the Federalism Assessment.

Conclusion

The FAA proposed to amend the

airworthiness standards for testing

balloon burners because test

requirements did not test the burner’s

most critical operating conditions. This

amendment will cut the cost to balloon

manufacturers seeking certification and

increase the current level of safety by

requiring more realistic tests.

For the reasons discussed in the

preamble, and based on the findings in

the Regulatory Flexibility Determination

and the International Trade Impact

Analysis, the FAA has determined that

this regulation is not significant under

Executive Order 12866.

In addition, the FAA certifies that this

regulation will not have a significant

economic impact, positive or negative,

on a substantial number of small entities

under the criteria of the Regulatory

Flexibility Act. This regulation is not

considered significant under DOT

Regulatory Policies and Procedures (44

FR 11034; February 26, 1979). A

regulatory evaluation of the regulation,

including a Regulatory Flexibility

Determination and International Trade

Impact Analysis, has been placed in the

docket. A copy may be obtained by

contacting the person identified under

FOR FURTHER INFORMATION CONTACT.

List of Subjects in 14 CFR Part 31

Aircraft, Aviation safety.

The Amendment

In consideration of the foregoing, the

Federal Aviation Administration

amends part 31 of the Federal Aviation

Regulations (14 CFR part 31) as follows:

PART 31—AIRWORTHINESS

STANDARDS: MANNED FREE

BALLOONS

1. The authority citation for part 31

continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701–

44702, 44704.

2. Section 31.47 is amended by

revising the heading and paragraphs (a)

and (d) to read as follows:
Federal Register / Vol. 61, No. 80 / Wednesday, April 24, 1996 / Rules and Regulations 18223

§ 31.47 Burners.

(a) If a burner is used to provide the

lifting means, the system must be

designed and installed so as to create a

fire hazard.

* * * * *

(d) The burner system (including the

burner unit, controls, fuel lines, fuel

cells, regulators, control valves, and

other related elements) must be

substantiated by an endurance test of at

least 40 hours. Each element of the

system must be installed and tested to

simulate actual balloon installation and

use.

(1) The test program for the main blast

valve operation of the burner must

include:

(i) Five hours at the maximum fuel

pressure for which approval is sought,

with a burn time for each one minute

cycle of three to ten seconds. The burn

time must be established so that each

burner is subjected to the maximum

thermal shock for temperature affected

elements;

(ii) Seven and one-half hours at an

intermediate fuel pressure, with a burn

time for each one minute cycle of three

to ten seconds. An intermediate fuel

pressure is 40 to 60 percent of the range

between the maximum fuel pressure

referenced in paragraph (d)(1)(i) of this

section and minimum fuel pressure

referenced in paragraph (d)(1)(iii);

(iii) Six hours and fifteen minutes at

the minimum fuel pressure for which

approval is sought, with a burn time for

each one minute cycle of three to ten

seconds;

(iv) Fifteen minutes of operation on

vapor, with a burn time for each one

minute cycle of at least 30 seconds; and

(v) Fifteen hours of normal flight

operation.

(2) The test program for the secondary

or backup operation of the burner must

include six hours of operation with a

burn time for each five minute cycle of

one minute at an intermediate fuel

pressure.

* * * * *

Issued in Washington, DC, on April 8,

1996.

David R. Hinson,

Administrator.

[FR Doc. 96–10004 Filed 4–23–96; 8:45 am]

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