Federal Aviation Administration (FAA), Department of Transportation (DOT).
Notice of proposed rulemaking (NPRM).
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing transport category airplanes. This proposed AD would require replacing any insulation blanket constructed of polyethyleneteraphthalate (PET) film, ORCON Orcofilm® AN–26 (hereafter “AN–26”) with a new insulation blanket. This proposed AD is prompted by reports of in-flight and ground fires on certain airplanes manufactured with insulation blankets covered with AN–26, which may contribute to the spread of a fire when ignition occurs from sources such as electrical arcing or sparking. We are proposing this AD to ensure that insulation blankets constructed of AN–26 are removed from the fuselage. Such insulation blankets could propagate a fire that is the result of electrical arcing or sparking.
We must receive comments on this proposed AD by June 3, 2005.
Use one of the following addresses to submit comments on this proposed AD.
• DOT Docket Web site: Go to
• Government-wide rulemaking Web site: Go to
• Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL–401, Washington, DC 20590.
• By fax: (202) 493–2251.
• Hand Delivery: Room PL–401 on the plaza level of the Nassif Building,
You can examine the contents of this AD docket on the Internet at
Sue Rosanske, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM–150S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055–4056; telephone (425) 917–6448; fax (425) 917–6590.
We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed under
We will post all comments we receive, without change, to
You can examine the AD docket on the Internet at
Based on research experiments and in-service experience in the mid-1990's, the FAA initiated an investigation into the adequacy of the existing Bunsen burner flammability criteria for thermal/acoustic insulation.
Thermal/acoustic insulation is usually constructed in the form of what is commonly referred to as a “blanket.” Insulation blankets are typically composed of:
1. A batting material generically referred to as fiberglass; and
2. A film covering to contain the batting and to resist moisture penetration.
Metallized polyethyleneteraphthalate (MPET) and AN–26 are specific manufacturers' examples of these film covering materials.
Our investigation included large-scale fire testing, as well as tests for ignitability; these tests covered a broad range of materials. By the late 1990's, we had concluded that the Bunsen burner test method required by the existing rules was not adequate. That is, the test method did not discriminate between materials with desirable and undesirable flammability characteristics under realistic in-service conditions. A new certification standard was therefore needed.
In order to develop a new standard, we had to quantify the potential hazard. This involved additional large scale fire testing and tests to correlate the large scale tests with a laboratory scale test method. A necessary element of any new certification test method is that it must screen out materials that would be considered unacceptable for future installation because those materials would create the potential hazard that the new test standard is intended to prevent. The new test standard was adopted into the regulations and includes changes to the operating rules for newly manufactured airplanes. (Reference “Improved Flammability Standards for Thermal/Acoustic Insulation Materials Used in Transport Category Airplanes” (68 FR 45046, July 31, 2003).) The operating rule changes become effective in September of this year.
In developing the new test standard, we also developed criteria by which materials already in service could be judged as safe to remain in service. This involved measuring their susceptibility to an ignition source (such as an electrical arc or sparks) and their tendency to propagate a fire once ignited.
Materials that are susceptible to ignition by electrical arc or sparks and that would propagate a fire are considered unsafe. Using these criteria, we have published airworthiness directives (AD) to address a particular material. The following ADs require removal of MPET:
• AD 2000–11–01, amendment 39–11749 (65 FR 34321, May 26, 2000), applicable to certain McDonnell Douglas Model DC–9–80 and MD–90–30 series airplanes, and Model MD–88 airplanes;
• AD 2000–11–02, amendment 39–11750 (65 FR 34341, May 26, 2000), applicable to certain McDonnell Douglas Model DC–10–10F, DC–10–15, DC–10–30, DC–10–30F, and DC–10–40 series airplanes, and Model MD–11 and –11F series airplanes; and
• AD 2003–08–10, amendment 39–13122 (68 FR 19326, April 21, 2003), applicable to certain Aerospatiale Model ATR42–500 series airplanes, and Model ATR72–102, –202, –212, and –212A series airplanes.
At that time, MPET was the only material identified that had demonstrated the propensity to propagate a fire from an ignition source such as electrical arcing and sparks. We indicated then that we would take the same action, should any other materials be identified.
Even though we did extensive testing on a variety of materials, we could not identify and test every material produced, as the permutations of material combinations were too extensive to accomplish such testing in a prudent time frame. As a result, we were not aware of AN–26 as a unique insulation material until a review of subsequent service data indicated that this material might not have adequate flammability resistance. We conducted a review of the service history and subjected AN–26 material to a variety of tests. In November 2003, we established that AN–26 could propagate a fire from an electrical arc. As part of our review, we also worked with industry to explore the potential ramifications of aging and contamination on material performance. Opinions differ on the significance of these effects. After careful consideration of this complex issue, we have concluded that the flammability characteristics of AN–26 are more a factor of fundamental material properties than a factor of aging or contamination.
We have received reports of in-flight and ground fires on certain Boeing Model 737, 747, 757, and 767 series airplanes that were manufactured with insulation material covered with AN–26. Investigation has revealed that AN–26 covered insulation blankets may contribute to the propagation of a fire. The results of extensive flammability testing, conducted by the airplane manufacturer and the FAA, revealed that even though AN–26 met the certification standards in place at the time of original certification in 1981, this type of insulation material will propagate a fire when subjected to electrical arcing and sparks. The FAA used the insulation blankets' response to electrical arcing and spark testing as the basis for identifying the unsafe condition with MPET and has determined that these same safety criteria are applicable to AN–26. In addition, research data have shown that contamination, such as dust, lint, grease, corrosion-inhibiting compounds, etc., can increase susceptibility to ignition and flame propagation.
Insulation blankets constructed of AN–26 installed throughout the fuselage, if not corrected, could propagate a fire that is the result of electrical arcing or sparking.
We have determined that Boeing's preferred supplier of insulation blankets produced blankets constructed of AN–26 between July 1981 and December 1988. Therefore, it is likely that these blankets are installed on almost all Boeing airplanes produced during that period, as listed in the following table:
Eleven Boeing Model 747–400 series airplanes were built in 1988 that are also likely to have AN–26 installed. However, the type certificate was not amended to include these airplanes until 1989. Therefore, these airplanes did not have an original Airworthiness Certificate or original Export Certificate of Airworthiness before January 1989.
The other affected airplanes were issued an original Airworthiness Certificate or original Export Certificate of Airworthiness between July 1981 and December 1988.
Unlike MPET, which is easily distinguishable from other types of insulation, AN–26 is similar in appearance to other types of insulation that are acceptable. At this time, there is no documented method for distinguishing between AN–26 and these other types of insulation.
The FAA issued Flight Standards Information Bulletin for Airworthiness (FSAW) 00–09, “Special Emphasis Inspection on Contamination of Thermal/Acoustic Insulation,” effective September 28, 2000, to ensure that operators have procedures defined in their approved maintenance programs for the inspection for contamination and corrective action. The airplane manufacturer also has recently revised its service letters alerting operators to methods for preventing and removing contamination.
We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD to require removing all insulation blankets within the pressurized areas of the affected airplanes and installing a new insulation blanket meeting the requirements of Section 25.856(a) of Title 14 of the Code of Federal Regulations (CFR) (14 CFR 25.856(a)). The proposed AD would also allow operators to develop methods for distinguishing between insulation blankets constructed of AN–26 and other materials. If the FAA's Seattle Aircraft Certification Office (ACO) approves such a method, operators would not be required to remove blankets they determine are not constructed of AN–26.
As of the effective date of this AD, paragraph (h)(1) of this proposed AD would prohibit installation of AN–26 insulation blankets. 14 CFR 91.613(b)(1), 121.312(e)(1), 125.113(c)(1), and 135.170(c)(1) already prohibit installation of this type of insulation blanket after September 2, 2005. Some international civil aviation authorities have not adopted similar regulations. Therefore, this prohibition is included in this proposed AD to inform them of the need to prevent such installation.
As of six months after the effective date of this AD, paragraph (h)(2) of this proposed AD would also prohibit re-installation of any insulation blanket that has been removed for any reason unless the insulation blanket either has been determined not to be constructed of AN–26, or has been modified to comply with 14 CFR 25.856(a). For example, during normal maintenance, operators frequently remove insulation to perform inspections and other maintenance actions on systems and structure located behind the insulation blanket. Under this proposal, when insulation is removed for this or any other purpose, it must either be determined not to be constructed of AN–26, or replaced with insulation meeting 14 CFR 25.856(a). This paragraph would require operators to correct the identified unsafe condition when they have an opportunity to do so.
The airplane manufacturer has been developing a proposed alternative method of compliance (AMOC) that involves modification of existing AN–26 insulation blankets. This method of compliance may significantly reduce the number of required replacement blankets and labor costs. The manufacturer has indicated that the service information for this method will be available in April 2006. We anticipate that the manufacturer's approach is similar to AMOCs approved for ADs 2000–11–01 and 2000–11–02. The criteria that will be used to evaluate proposed modifications of existing AN–26 insulation blankets (in-place) can be obtained from the Manager, Seattle ACO, upon request.
There are about 1,613 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with the proposed replacement, if necessary. The average labor rate is $65 per hour.
The Regulatory Flexibility Act of 1980 (RFA) establishes “as a principle of regulatory issuance that agencies shall endeavor, consistent with the objective of the rule and of applicable statutes, to fit regulatory and informational requirements to the scale of the business, organizations, and governmental jurisdictions subject to regulation.” To achieve that principle, the RFA requires agencies to solicit and consider flexible regulatory proposals and to explain the rationale for their actions. The RFA covers a wide-range of small entities, including small businesses, not-for-profit organizations and small governmental jurisdictions.
Agencies must perform a review to determine whether a proposed or final rule will have a significant economic impact on a substantial number of small entities. If the agency determines that it will, the agency must prepare a regulatory flexibility analysis as described in the Act.
The proposed AD would require operators of certain Boeing transport category airplanes, including about 20 small business operators, to retrofit their airplanes. We believe that this proposed AD would have a significant impact on a substantial number of small entities. Accordingly, an initial regulatory flexibility analysis, as required by the RFA, is included as part of the Initial Regulatory Analysis that is in the docket.
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect 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.
For the reasons discussed above, I certify that the proposed regulation:
1. Is not a “significant regulatory action” under Executive Order 12866;
2. Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and
3. Would have a significant economic impact on a substantial number of small entities, and as a result, an initial regulatory flexibility analysis has been conducted.
See the
Air transportation, Aircraft, Aviation safety, Safety.
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
1. The authority citation for part 39 continues to read as follows:
49 U.S.C. 106(g), 40113, 44701.
2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):
(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by June 3, 2005.
(b) None.
(c) This AD applies to Boeing airplanes, certificated in any category, specified in paragraphs (c)(1) and (c)(2) of this AD.
(1) Boeing airplanes listed in Table 1 of this AD, having an original Airworthiness Certificate or original Export Certificate of Airworthiness issued between July 1981 and December 1988 inclusive.
(2) Boeing Model 747–400 series airplanes, serial numbers 23719, 23720, 23814, 23816, 23817, 23818, 23819, 23820, 23999, 24061, and 24062.
(d) This AD was prompted by reports of in-flight and ground fires on certain airplanes manufactured with insulation blankets covered with a specific polyethyleneteraphthalate (PET), ORCON Orcofilm® AN–26 (all variants, including AN–26, AN–26A, and AN–26B), hereafter referred to as “AN–26”, which may contribute to the spread of a fire when ignition occurs from sources such as electrical arcing or sparking. We are issuing this AD to ensure that insulation blankets constructed of AN–26 are removed from the fuselage. Such insulation blankets could propagate a fire that is the result of electrical arcing or sparking.
(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
(f) Except as provided in paragraph (g) of this AD, within 72 months after the effective date of this AD, remove all insulation blankets from the pressurized areas of the fuselage and install a new insulation blanket using applicable maintenance manual procedures. The new insulation blankets must comply with 14 Code of Federal Regulations (CFR) 25.856(a). The areas where the affected insulation blankets are installed include, but are not limited to, the following areas:
(1) Crown area of the airplane;
(2) Areas behind flight deck panels and circuit breaker panels;
(3) Areas behind sidewalls, lavatories, closets, and galleys;
(4) Cargo compartment areas;
(5) Air ducting;
(6) Waste and water tubing; and
(7) Areas attached to the underside of floor panels.
(g) The actions described in paragraph (f) are not required for any insulation blanket that is determined not to be constructed of AN–26, using a method approved by the Manager, Seattle Aircraft Certification Office (ACO).
Insulation material that is part-marked with a date of manufacture indicating that it was manufactured before July 1981 or after December 1988 is not constructed of AN–26.
(h)(1) As of the effective date of this AD, no person may install any insulation blanket constructed of AN–26 on any airplane unless it has been modified to comply with 14 CFR 25.856(a), in accordance with a method approved by the Manager, Seattle ACO.
(2) As of six months after the effective date of this AD, if any insulation blanket is removed for any reason, it may not be re-installed unless:
(i) It has been determined not to be constructed of AN–26 using a method approved by the Manager, Seattle ACO; or
(ii) It has been modified to comply with 14 CFR 25.856(a), in accordance with a method approved by the Manager, Seattle ACO.
(i) The Manager, Seattle ACO, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.