[Federal Register Volume 61, Number 80 (Wednesday, April 24, 1996)]
[Rules and Regulations]
[Pages 18220-18223]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-10004]




[[Page 18219]]


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Part V





Department of Transportation





_______________________________________________________________________



Federal Aviation Administration



_______________________________________________________________________



14 CFR Part 31



Airworthiness Standards; Manned Free Balloon Burner Testing; Final Rule

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

[[Page 18220]]



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 
Sec. 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 Sec. 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 Sec. 31.47. The 
FAA will address these comments in the order they were submitted.
    Concerning proposed Sec. 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 Sec. 31.47(d)(1)(i) was to allow each 
applicant to pre-determine 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

[[Page 18221]]

time was to ensure that the burner being tested is subjected to the 
maximum thermal shock, the regulatory text of Sec. 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 Sec. 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 Sec. 31.47(d)(1)(iv) will retain the 15 minute standard as 
proposed.
    The same commenter offers the following suggested rewrite for 
Sec. 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 Sec. 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 
Sec. 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, 
Sec. 31.47(d)(2) is adopted as proposed.
    The commenter recommends adding new paragraphs (3) and (4) to 
Sec. 31.47(d). The recommendation for a new Sec. 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 Sec. 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 Sec. 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 Sec. 31.47(d) reads as follows:


[[Page 18222]]


    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 
Sec. 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 Sec. 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 Sec. 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:

[[Page 18223]]

Sec. 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]
BILLING CODE 4910-13-M