96-10004. Airworthiness Standards; Manned Free Balloon Burner Testing  

  • [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]
    
    
    
    
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    Part V
    
    
    
    
    
    Department of Transportation
    
    
    
    
    
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    Federal Aviation Administration
    
    
    
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    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
    
    

Document Information

Effective Date:
5/24/1996
Published:
04/24/1996
Department:
Federal Aviation Administration
Entry Type:
Rule
Action:
Final rule.
Document Number:
96-10004
Dates:
May 24, 1996.
Pages:
18220-18223 (4 pages)
Docket Numbers:
Docket No. 27543, Amendment No. 31-7
RINs:
2120-AE87: Manned Free Balloons
RIN Links:
https://www.federalregister.gov/regulations/2120-AE87/manned-free-balloons
PDF File:
96-10004.pdf
CFR: (4)
14 CFR 31.47(d)
14 CFR 31.47(d)(2)
14 CFR 31.47(d)(1)(v)
14 CFR 31.47