Airworthiness Directives; Gulfstream Model G-159 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-138-AD]

RIN 2120-AA64

Airworthiness Directives; Gulfstream Model G-159 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 Gulfstream Model G-159 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-138-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,

Small Airplane Directorate, Atlanta Aircraft Certification Office, One

Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia

30349.

FOR FURTHER INFORMATION CONTACT: Neil Berryman, Aerospace Engineer,

Systems and Flight Test Branch, ACE-116A, FAA, Small Airplane

Directorate, Atlanta Aircraft Certification Office, One Crown Center,

1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349; telephone

(770) 703-6098; fax (770) 703-6097.

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-138-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-138-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 Gulfstream Model G-159 series airplanes, was published as a

notice of proposed rulemaking (NPRM) in the Federal Register on July

16, 1999 (64 FR 38341). That NPRM would have required revising the

Airplane Flight Manual (AFM) to include requirements for activation of

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

[[Page 62992]]

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 recognizes that early

activation of the ``older'' pneumatic deicing boots may create the

hazard of ice bridging on the ``older'' systems. The FAA also

acknowledges that ``older'' boots may be susceptible to ice bridging

because they operate at lower pressure and have larger diameter tubes.

The FAA concurs that requiring 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 Gulfstream Model G-159 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. If other

solutions are identified, the FAA may consider further rulemaking.

Additionally, the FAA is issuing a similar supplemental NPRM to

accommodate certain McDonnell Douglas Model DC-3 and DC-4 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 141 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 AFM revisions, 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 $16,920, 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 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:

Gulfstream Aerospace Corporation (Formerly Grumman): Docket 99-NM-

138-AD.

Applicability: Model G-159 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

[[Page 62993]]

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 are 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, Atlanta Aircraft Certification

Office, FAA, Small Airplane Directorate. The request shall be

forwarded through an appropriate FAA Operations Inspector, who may

add comments and then send it to the Manager, Atlanta ACO.

Note 2: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Atlanta 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. 99-30149 Filed 11-17-99; 8:45 am]

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