Airworthiness Directives; McDonnell Douglas Model MD-90-30 Airplanes, 49180-49183 [E7-16674]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 72, Number 166 (Tuesday, August 28, 2007)]
[Rules and Regulations]
[Pages 49180-49183]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-16674]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-194-AD; Amendment 39-15177; AD 2007-17-19]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model MD-90-30 
Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain McDonnell Douglas Model MD-90-30 airplanes, that 
requires repetitive inspections and functional tests of the static port 
heater assemblies, and corrective actions if necessary. The actions 
specified by this AD are intended to prevent an electrical short of the 
static port heater from sparking and igniting the insulation blanket 
adjacent to the static port heater, which could result in smoke and/or 
fire in the cabin area. This action is intended to address the 
identified unsafe condition.

DATES: Effective October 2, 2007.
    The incorporation by reference of a certain publication listed in 
the regulations is approved by the Director of the Federal Register as 
of October 2, 2007.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplanes, Long Beach Division, 3855 
Lakewood Boulevard, Long Beach, California 90846, Attention: Data and 
Service Management, Dept. C1-L5A (D800-0024). This information may be 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue 
SW., Renton, Washington; or at the FAA, Los Angeles Aircraft 
Certification Office, 3960 Paramount Boulevard, Lakewood, California.

FOR FURTHER INFORMATION CONTACT: Natalie Phan-Tran, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft 
Certification Office, 3960 Paramount Boulevard, Lakewood, California 
90712-4137; telephone (562) 627-5343; fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain McDonnell Douglas Model 
MD-90-30 airplanes was published as a supplemental notice of proposed 
rulemaking (NPRM) in the Federal Register on December 20, 2005 (70 FR 
75435). That action proposed to require repetitive inspections and 
functional tests of the static port heater assemblies, repetitive 
inspections of the static port heaters and insulators, and corrective 
actions if necessary.

Actions Since Issuance of Supplemental NPRM

    We proposed in paragraph (b)(2) of the supplemental NPRM to require 
repetitive inspections for proper installation of the static port 
heaters and insulation. This proposal was in response to a National 
Transportation Safety Board (NTSB) comment on the original NPRM. 
However, we have re-assessed the safety implications of the issue based 
on additional information that we received from Boeing. Although we 
understand the NTSB's concern, we have determined that the inspections 
in paragraph (b)(2) of the supplemental NPRM are not necessary to 
address the identified unsafe condition. We have revised paragraph (b) 
of this AD to remove the requirement to inspect for proper installation 
for the following reasons.
    We have concluded that the incorrect stacking of the heater 
assembly does not contribute to the heater connector wire damage and is 
therefore not a safety concern.
    We based our original decision to incorporate a one-time inspection 
for incorrect stacking into the original NPRM on the following 
statement made to the FAA in Boeing Letter C1-L4L-03-0700, dated June 
3, 2003.

    Boeing's evaluation included Delta's recommendation to redesign 
the ``* * * heater resistance wires * * *'' or heater element to 
incorporate larger bend radii. The problems of excessive localized 
heating near the bend radii of the element encountered by Delta may 
be attributed to heaters that were assembled improperly due to the 
AMM error. Delta's statements in its report indicate finding heater 
blankets improperly assembled. Boeing concurs with Delta that this 
assembly error would cause excessive heating and Boeing also 
believes this condition could lead to delamination or other damage 
in the bend radii areas.

    Then, in the supplemental NPRM, we agreed with the NTSB 
recommendation to require repetitive inspections to address any 
incorrect stacking that might occur in the future.
    After Boeing commented on the supplemental NPRM (see ``Comments'' 
section below), we contacted Boeing to clarify its comments. At the 
same time, in order to better understand the need for a repetitive 
inspection for proper installation as the NTSB recommended, we asked 
Boeing to provide us with additional information on the cause and 
effect of improper installation (incorrect stacking).
    We specifically requested that Boeing clarify the definition of 
``excessive heating'' and ``other damage in the bend radii areas.'' 
Boeing confirmed that the bend radii area of the heater assembly is the 
internal heating element bend radii, within the laminated elastomer and 
is not the bend radii of the connector wire. Based on this statement, 
we concluded that the incorrect stacking of the heater as we understood 
before does not contribute to heater connector wire damage.
    Our evaluation of the additional information has resulted in a 
better understanding of ``excessive heating.'' We determined that 
improper stack-up of the static port heater might cause the heater 
assembly to run longer at the

[[Page 49181]]

high wattage setting in order to heat the static plate to the proper 
temperature. The heater assembly circuit design limits the absolute 
temperature that the element can reach. Thus, the heater assembly 
cannot reach temperatures significantly higher than the intended 
operating temperatures. Additionally, the heater circuit design 
incorporates a 310 [deg]F thermal fuse. However, the additional duty 
time or cycles caused by the improper stack-up might accelerate the 
normal aging of the heater assembly. Based on the above information, 
our previous conclusion that ``excessive heating'' could damage the 
heater connector wire is incorrect.
    Furthermore, Boeing addressed the improper stack-up of the static 
port heater assembly in McDonnell Douglas All Operator Letter (AOL) 9-
2186, dated August 15, 1991. The AOL notified the operators of an 
incorrect depiction of the heater/insulator installation in the DC-9 
and MD-80 Airplane Maintenance Manuals (AMMs), which were also revised 
and corrected in 1991. We are aware of no subsequent reports of 
improper stack-up of the static port heater assembly.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Request To Withdraw the Supplemental NPRM

    Boeing requests that the supplemental NPRM be withdrawn. Boeing 
considers its comments on the original NPRM still valid and offers 
these following additional comments on the supplemental NPRM.
    Boeing contends that the unsafe condition no longer exists. Boeing 
states that the unsafe condition was addressed by Boeing Alert Service 
Bulletin MD90-30A023, including Appendix, dated March 14, 2001 (for 
Model MD-90-30 airplanes), which was mandated by AD 2001-10-11, 
amendment 39-12237 (66 FR 28651, May 24, 2001), and by Boeing Alert 
Service Bulletin MD80-30A092, including Appendix, dated March 14, 2001 
(for Model DC-9-81, -82, -83, and -87 airplanes, and Model MD-88 
airplanes), which was mandated by AD 2001-10-10, amendment 39-12236 (66 
FR 28643, May 24, 2001). Boeing states that those ADs require 
inspecting the wiring of the primary and alternate static port heaters, 
determining if the type of insulation blanket installed is metallized 
Mylar, and modifying the insulation blankets if necessary.
    Boeing also states that a review of operators' reports indicates 
only two events resulted in smoke in the cabin, both on one operator's 
MD-88 airplanes, with one report stating a smoke smell was ``evident.'' 
In response, Boeing issued the service bulletins described previously. 
Boeing notes that ``in the three years since the release of these 
service bulletins and the related ADs, no other static port heater 
smoke/fire events have been reported from the entire MD-80/90 fleet.''
    Boeing concludes that the unsafe condition no longer exists, and 
that the actions in the supplemental NPRM are purely an enhancement. 
Therefore, Boeing requests that the supplemental NPRM be withdrawn.
    We do not agree with Boeing's request to withdraw the supplemental 
NPRM. Although no other static port heater smoke/fire events have been 
reported since all metallized Mylar insulation blankets were replaced 
with other insulation blankets such as Tedlar, the potential for arcing 
from an electrical short of the static port heater connector wire still 
exists.
    As previously stated, we requested clarification of this request to 
withdraw the supplemental NPRM in an ex parte communication with 
Boeing.
    Boeing stated that it addressed the potential for fire by removing 
material known to ignite easily and propagate fire. Boeing concluded 
that the ignition source in the one event in 1999 was of extremely low 
energy. The residual risk created by the potential for the low energy 
arcing of the wire identified in the event does not, in itself, create 
an undue risk. However, Boeing acknowledges the FAA's intent to further 
reduce risk by requiring the actions specified in paragraph (b)(1) of 
the supplemental NPRM. Boeing recommends that operators perform a 
general visual inspection and the functional test (health check) in 
accordance with Boeing Service Bulletins MD90-30-026 and MD80-30-097.
    Therefore, it is Boeing's position that incorporating the 
inspections/tests, specified in paragraph (b)(1) of the supplemental 
NPRM, into the FAA-approved Maintenance Planning Document(s) is more 
appropriate.
    In regard to the general visual inspection to verify stack-up 
specified in paragraph (b)(2) of the supplemental NPRM, Boeing stated 
that stack-up issues are not applicable to the alternate static port 
heater assembly. As stated previously, it is Boeing's assessment that 
improper stack-up of the primary static port assembly will not increase 
the potential for fire as described. Therefore, Boeing disagrees with 
the intent of paragraph (b)(2).
    We concur with Boeing's recommendation that to further reduce risk, 
operators should perform a general visual inspection and functional 
test in accordance with Boeing Service Bulletin MD90-30-026, Revision 
1, dated May 27, 2005. However, we do not agree that incorporation of 
the inspections/tests into the applicable FAA-approved Maintenance 
Planning Document(s) is more appropriate than issuance of this AD. We 
consider issuance of an AD necessary because ADs are the means to 
mandate accomplishment of procedures and adherence to specific 
compliance times.
    We have determined, based on the above comments, that we will issue 
this AD with the requirement of repetitive inspections and the 
functional tests, as proposed, in accordance with Boeing Service 
Bulletin MD90-30-026, Revision 1, dated May 27, 2005, to identify and 
remove marginal static port heaters before they fail and generate 
sparks.
    Based on the technical and economic information provided earlier, 
we do agree with Boeing that inspection of the heater and insulator for 
incorrect stacking is not necessary. We have revised paragraph (b) of 
this AD accordingly.

Clarification of Alternative Method of Compliance (AMOC) Paragraph

    We have revised this action to clarify the appropriate procedure 
for notifying the principal inspector before using any approved AMOC on 
any airplane to which the AMOC applies.

Explanation of Change to Cost Impact

    After the supplemental NPRM was issued, we reviewed the figures we 
have used over the past several years to calculate AD costs to 
operators. To account for various inflationary costs in the airline 
industry, we find it necessary to increase the labor rate used in these 
calculations from $65 per work hour to $80 per work hour. The cost 
impact information, below, reflects this increase in the specified 
hourly labor rate.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

[[Page 49182]]

Cost Impact

    There are approximately 116 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 22 airplanes of U.S. registry 
are affected by this AD.
    It will take approximately 1 work hour per airplane to accomplish 
the general visual inspection for wire damage and functional test, at 
an average labor rate of $80 per work hour. Based on these figures, the 
cost impact of the inspection for wire damage and functional test on 
U.S. operators is estimated to be $1,760, or $80 per airplane, per 
inspection cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the requirements of this 
AD action, and that no operator would accomplish those actions in the 
future if this AD were not adopted. The cost impact figures discussed 
in AD rulemaking actions represent only the time necessary to perform 
the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

Authority for This Rulemaking

    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.

Regulatory Impact

    The regulations adopted herein will 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

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


Sec.  39.13  [Amended]

0
2. Section 39.13 is amended by adding the following new airworthiness 
directive:

2007-17-19 McDonnell Douglas: Amendment 39-15177. Docket 2003-NM-
194-AD.
    Applicability: Model MD-90-30 airplanes, certificated in any 
category, as identified in Boeing Service Bulletin MD90-30-026, 
Revision 1, dated May 27, 2005.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent an electrical short of the static port heater from 
sparking and igniting the insulation blanket adjacent to the static 
port heater, which could result in smoke and/or fire in the cabin 
area, accomplish the following:

Service Bulletin References

    (a) The term ``service bulletin,'' as used in this AD, means the 
Accomplishment Instructions of Boeing Service Bulletin MD90-30-026, 
Revision 1, dated May 27, 2005.

Inspection and Functional Test

    (b) Within 18 months after the effective date of this AD, 
perform a general visual inspection of the left and right primary 
and alternate static port heater assemblies for wire damage; and 
perform a functional test of the left and right primary and 
alternate static port heater assemblies; in accordance with the 
service bulletin. Repeat the actions thereafter at intervals not to 
exceed 48 months.

    Note 1: For the purposes of this AD, a general visual inspection 
is: ``A visual examination of an interior or exterior area, 
installation or assembly to detect obvious damage, failure or 
irregularity. This level of inspection is made from within touching 
distance unless otherwise specified. A mirror may be necessary to 
ensure visual access to all surfaces in the inspection area. This 
level of inspection is made under normal available lighting 
conditions such as daylight, hangar lighting, flashlight or drop-
light and may require removal or opening of access panels or doors. 
Stands, ladders or platforms may be required to gain proximity to 
the area being checked.''

Wire Damage or Heater Failures

    (c) If wire damage is found and/or the heater assembly fails the 
functional test during the general visual inspection and functional 
test required by paragraph (b) of this AD: Before further flight, 
replace the damaged or inoperative static port heater assembly with 
a new or serviceable static port heater assembly in accordance with 
the service bulletin.

Actions Accomplished According to Previous Issue of Service Bulletin

    (d) Actions accomplished before the effective date of this AD 
according to Boeing Service Bulletin MD90-30-026, dated February 15, 
2002, are considered acceptable for compliance with the 
corresponding actions specified in this AD.

Alternative Methods of Compliance (AMOCs)

    (e)(1) In accordance with 14 CFR 39.19, the Manager, Los Angeles 
Aircraft Certification Office (ACO), is authorized to approve 
alternative methods of compliance for this AD.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

Incorporation by Reference

    (f) Unless otherwise specified in this AD, the actions must be 
done in accordance with Boeing Service Bulletin MD90-30-026, 
Revision 1, dated May 27, 2005. This incorporation by reference was 
approved by the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR part 51. To get copies of this service 
information, contact Boeing Commercial Airplanes, Long Beach 
Division, 3855 Lakewood Boulevard, Long Beach, California 90846, 
Attention: Data and Service Management, Dept. C1-L5A (D800-0024). To 
inspect copies of this service information, go to the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or 
to the FAA, Los Angeles Aircraft Certification Office, 3960 
Paramount

[[Page 49183]]

Boulevard, Lakewood, California; or to the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at the NARA, call (202) 741-6030, or go to https://
www.archives.gov/federal_register/code_of_federal_regulations/
ibr_locations.html.

Effective Date

    (g) This amendment becomes effective on October 2, 2007.

    Issued in Renton, Washington, on August 14, 2007.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-16674 Filed 8-27-07; 8:45 am]
BILLING CODE 4910-13-P