[Federal Register Volume 64, Number 222 (Thursday, November 18, 1999)]
[Proposed Rules]
[Pages 62993-62995]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30150]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-139-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Models DC-3 and DC-4 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to certain McDonnell Douglas Models DC-3 and 
DC-4 series airplanes, that would have required revising the Airplane 
Flight Manual (AFM) to include requirements for activation of the 
airframe pneumatic deicing boots. That proposal was prompted by reports 
of inflight incidents and an accident that occurred in icing conditions 
where the airframe pneumatic deicing boots were not activated. This new 
action revises the proposed rule by adding an inspection to determine 
the type of pneumatic deicing boots, and requiring the AFM change only 
for those airplanes equipped with ``modern'' boots. The actions 
specified by this new proposed AD are intended to ensure that 
flightcrews activate the pneumatic wing and tail deicing boots at the 
first signs of ice accumulation. This action will prevent reduced 
controllability of the aircraft due to adverse aerodynamic effects of 
ice adhering to the airplane prior to the first deicing cycle.

DATES: Comments must be received by December 13, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-139-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, 
Transport Airplane Directorate, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137.

FOR FURTHER INFORMATION CONTACT: Albert Lam, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane 
Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount 
Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5346; 
fax (562) 627-5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-NM-139-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 99-NM-139-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain McDonnell Douglas Models DC-3 and DC-4 series airplanes, was 
published as a notice of proposed rulemaking (NPRM) in the Federal 
Register on July 16, 1999 (64 FR 38335). That NPRM would have required 
revising the Airplane Flight Manual (AFM) to include requirements for 
activation of

[[Page 62994]]

the airframe pneumatic deicing boots. That NPRM was prompted by reports 
of inflight incidents and an accident that occurred in icing conditions 
where the airframe pneumatic deicing boots were not activated. The 
actions specified by that proposed AD are intended to ensure that 
flightcrews activate the pneumatic wing and tail deicing boots at the 
first signs of ice accumulation. Such ice accumulation, if not 
corrected, could result in reduced controllability of the aircraft due 
to adverse aerodynamic effects of ice adhering to the airplane prior to 
the first deicing cycle.

Distinction Between ``Older'' and ``Modern'' Boots

    For the purposes of this supplemental NPRM, the FAA considers that 
a definition of the terms ``older'' and ``modern'' pneumatic deicing 
boots is necessary. ``Modern'' pneumatic boot systems may be 
characterized by short segmented, small diameter tubes, which are 
operated at relatively high pressures [18-23 pounds per square inch 
(psi)] by excess bleed air that is provided by turbine engines. 
``Older'' pneumatic boot systems may be characterized by long, 
uninterrupted, large diameter tubes, which were operated at low 
pressures by engine driven pneumatic pumps whose pressure varied with 
engine revolutions per minute (rpm). This low pressure coupled with 
long and large diameter tubes caused early de-ice systems to have very 
lengthy inflation and deflation cycles and dwell times. (Dwell time is 
the period of time that the boot remains fully expanded following the 
completion of the inflation cycle until the beginning of the deflation 
cycle.) The FAA has specified these definitions in a new Note 1 in the 
final rule.

Actions Since Issuance of Previous Proposal

    Due consideration has been given to the comments received in 
response to the NPRM:
    Two commenters request that the proposed rules applying to 
Gulfstream Model G-159 series airplanes and McDonnell Douglas Model DC-
3 and DC-4 series airplanes be withdrawn. Both commenters state that 
those airplane models do not meet the common definition of the word 
``modern.'' One commenter states that the current AFM specifically 
directs the flight crew to wait for \1/2\-inch of ice before activating 
the boots. Further, the commenter asserts that the current procedure 
was developed during certification and is the basis for the airplane's 
approval for flight into known icing. Additionally, the commenters 
assert that the in-service safety records for more than 40 years 
indicate that the existing procedures are appropriate for these 
airplanes. The commenters conclude that the proposed AFM revision is in 
direct opposition to the certification findings.
    As discussed in the original NPRM, the FAA acknowledges that early 
activation of the ``older'' pneumatic deicing boots may create the 
hazard of ice bridging on the ``older'' systems. The FAA considers that 
``older'' boots may be susceptible to ice bridging because the boots 
operate at lower pressure and have larger diameter tubes. The FAA 
concurs that requiring the activation of the boots at the first sign of 
icing may actually introduce an unsafe condition on those airplanes.
    In order to address this issue, the FAA is taking the following 
steps. First, to accommodate certain McDonnell Douglas Model DC-3 and 
DC-4 series airplanes that may be equipped with the ``older'' pneumatic 
deicing boot system, the FAA is issuing this supplemental Notice of 
Proposed Rulemaking (NPRM). This supplemental NPRM proposes to require 
an inspection to determine which type of pneumatic deicing boots are 
installed on the airplanes, and to require operation of the boots at 
the first sign of ice accretion if the airplanes have been retrofitted 
with ``modern'' boots. Second, for aircraft with ``older'' pneumatic 
boots installed, the FAA will continue to investigate other solutions 
to the unsafe condition of reduced handling qualities or 
controllability of the airplane due to ice accumulations on the 
protected surfaces. The FAA may consider further rulemaking if it is 
determined that there is an existing unsafe condition on those 
airplanes equipped with ``older'' pneumatic deicing boot systems.
    Additionally, the FAA is issuing a similar supplemental NPRM to 
accommodate certain Gulfstream Model G-159 series airplanes that may be 
equipped with ``older'' pneumatic deicing boot systems.
    In response to the commenter's assertion that existing procedures 
are appropriate for these airplanes, the FAA has reviewed the icing-
related incident history of certain airplanes, and has determined that 
icing incidents may have occurred because pneumatic deicing boots were 
not activated at the first evidence of ice accretion. As a result, the 
handling qualities or the controllability of the airplane may have been 
reduced due to the accumulated ice. In the previous NPRM, the FAA also 
discussed an accident that occurred as a result of the failure of the 
flight crew to activate the wing and tail pneumatic deicing boots.
    Although there may have been no reported cases of incidents or 
accidents on a specific airplane model, the potential still exists for 
reduced controllability of all airplanes equipped with pneumatic 
deicing boots due to adverse aerodynamic effects of ice adhering to the 
airplane. This supplemental NPRM addresses that unsafe condition.

Conclusion

    Since this change expands the scope of the originally proposed 
rule, the FAA has determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment.

Cost Impact

    The FAA estimates that 166 airplanes of U.S. registry would be 
affected by this proposed AD.
    The FAA estimates that it would take approximately 2 work hours per 
airplane to accomplish the proposed actions, at the average labor rate 
of $60 per work hour. Based on these figures, the cost impact of the 
proposed AD on U.S. operators is estimated to be $19,920, or $120 per 
airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this AD were not adopted.

Regulatory Impact

    The regulations proposed herein would 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 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this 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) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by

[[Page 62995]]

contacting the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

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

PART 39--AIRWORTHINESS DIRECTIVES

    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]

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

McDonnell Douglas: Docket 99-NM-139-AD.

    Applicability: Models DC-3 and DC-4 series airplanes equipped 
with pneumatic deicing boots, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To ensure that flightcrews activate the wing and tail pneumatic 
deicing boots at the first signs of ice accumulation on the 
airplane, accomplish the following:

    Note 1: For the purposes of this AD, the following definitions 
of ``older'' and ``modern'' apply:
    ``Modern'' pneumatic boot systems may be characterized by short 
segmented, small diameter tubes, which are operated at relatively 
high pressures [18-23 pounds per square inch (psi)] by excess bleed 
air that is provided by turbine engines. ``Older'' pneumatic boot 
systems may be characterized by long, uninterrupted, large diameter 
tubes, which were operated at low pressures by engine driven 
pneumatic pumps whose pressure varied with engine revolutions per 
minute (rpm). This low pressure coupled with long and large diameter 
tubes caused early de-ice systems to have very lengthy inflation and 
deflation cycles and dwell times. (Dwell time is the period of time 
that the boot remains fully expanded following the completion of the 
inflation cycle until the beginning of the deflation cycle.)
    (a) Within 10 days after the effective date of this AD: Perform 
a visual inspection to determine if the type of pneumatic deicing 
boots installed is either ``older'' or ``modern'' boots.
    (1) For those airplanes equipped with ``older'' pneumatic 
deicing boots, no further action is required by this AD.
    (2) For those airplanes equipped with ``modern'' pneumatic 
deicing boots, within 10 days after the inspection required by 
paragraph (a) of this AD: Revise the Limitations Section of the FAA-
approved Airplane Flight Manual (AFM) to include the following 
requirements for activation of the ice protection systems. This may 
be accomplished by inserting a copy of this AD in the AFM.
    `` Except for certain phases of flight where the AFM 
specifies that deicing boots should not be used (e.g., take-off, 
final approach, and landing), compliance with the following is 
required.
     Wing and Tail Leading Edge Pneumatic Deicing Boot 
System, if installed, must be activated:

--At the first sign of ice formation anywhere on the aircraft, or 
upon annunciation from an ice detector system, whichever occurs 
first; and
--The system must either be continued to be operated in the 
automatic cycling mode, if available; or the system must be manually 
cycled as needed to minimize the ice accretions on the airframe.

     The wing and tail leading edge pneumatic deicing boot 
system may be deactivated only after leaving icing conditions and 
after the airplane is determined to be clear of ice.''
    (b) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Los Angeles Aircraft Certification 
Office, Transport Airplane Directorate. The request shall be 
forwarded through an appropriate FAA Operations Inspector, who may 
add comments and then send it to the Manager, Los Angeles ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (c) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

    Issued in Renton, Washington, on November 10, 1999.
John J. Hickey,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-30150 Filed 11-17-99; 8:45 am]
BILLING CODE 4910-13-P