21982 Federal Register / Vol. 61, No. 93 / Monday, May 13, 1996 / Proposed Rules

provision, regardless of whether it has been

modified, altered, or repaired in the area

subject to the requirements of this AD. For

sailplanes that have been modified, altered,

or repaired so that the performance of the

requirements of this AD is affected, the

owner/operator must request approval for an

alternative method of compliance in

accordance with paragraph (c) of this AD.

The request should include an assessment of

the effect of the modification, alteration, or

repair on the unsafe condition addressed by

this AD; and, if the unsafe condition has not

been eliminated, the request should include

specific proposed actions to address it.

Compliance: Required within the next 50

hours time-in- service (TIS) after the effective

date of this AD, unless already accomplished.

To prevent the rudder bearing support

bracket from cracking, which could cause

loss of rudder control and possible loss of the

sailplane, accomplish the following:

(a) Inspect (one time) the rudder bearing

support bracket with a 10x magnifying glass

for any visible cracks in accordance with the

Actions section of Flugtechnik service

bulletin (SB) HB–23/19/91, dated October 5,

1991.

(1) If cracks are found, prior to further

flight, replace the rudder bearing support

bracket with a new support bracket that has

3 bolt holes in accordance with the Actions

section of Flugtechnik SB HB–23/19/91,

dated October 5, 1991.

(2) If no cracks are found, modify the

rudder bearing support bracket by installing

a third bolt (part number M6x30) or replace

the bracket with a new bracket that has 3 bolt

holes in accordance with the Actions section

of Flugtechnik SB HB–23/19/91, dated

October 5, 1991.

(b) 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 sailplane

to a location where the requirements of this

AD can be accomplished.

(c) An alternative method of compliance or

adjustment of the compliance time that

provides an equivalent level of safety may be

approved by the Manager, Small Airplane

Directorate, Aircraft Certification Service,

FAA, 1201 Walnut, suite 900, Kansas City,

Missouri 64106. The request shall be

forwarded through an appropriate FAA

Maintenance Inspector, who may add

comments and then send it to the Manager,

Small Airplane Directorate.

NOTE 2: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Small Airplane Directorate

Aircraft Certification Office.

(d) All persons affected by this directive

may obtain copies of this document referred

to herein upon request to H.B. Flugtechnik

GmbH, attn: Dr. Adolf Scharf STR, 42 P.F. 74,

A–4053, Haid, Austria; or may examine this

document at the FAA, Central Region, Office

of the Assistant Chief Counsel, Room 1558,

601 E. 12th Street, Kansas City, Missouri

64106.

Issued in Kansas City, Missouri, on May 6,

1996.

Henry A. Armstrong,

Acting Manager, Small Airplane Directorate,

Aircraft Certification Service.

[FR Doc. 96–11880 Filed 5–10–96; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 96–NM–63–AD]

RIN 2120–AA64

Airworthiness Directives; Gates Learjet

Model 35 and 36 Series Airplanes

Modified by Raisbeck STC SA766NW

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

adoption of a new airworthiness

directive (AD) that is applicable to

certain Gates Learjet Model 35 and 36

series airplanes that have been modified

in accordance with Raisbeck

Supplemental Type Certificate (STC)

SA766NW. This proposal would require

a reduction of the maximum operating

limit speed on the affected airplanes to

prevent encountering certain potentially

hazardous conditions. This proposal is

prompted by reports of incidents of

aileron buffet or buzz experienced

during high speed cruise. The actions

specified by the proposed AD are

intended to prevent aileron buffet or

buzz conditions, which can result in the

deterioration of the aircraft lateral

control system characteristics to an

unacceptable level.

DATES: Comments must be received by

June 24, 1996.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 96–NM–

63–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.

Information concerning the subject of

this rulemaking action may be obtained

from Jet Air Corporation, P.O. Box 245,

Bellevue, Washington 98009.

Information concerning this rulemaking

action may be examined at the FAA,

Transport Airplane Directorate, 1601

Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Stan

Wood, Aerospace Engineer, Airframe

Branch, ANM–120S, FAA, Seattle

Aircraft Certification Office, 1601 Lind

Avenue, SW., Renton, Washington;

telephone (206) 227–2772; fax (206)

227–1181.

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 96–NM–63–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–103, Attention: Rules Docket No.

96–NM–63–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

On July 23, 1985, the FAA issued AD

85–16–04, amendment 39–5110 (50 FR

30803, July 30, 1985), which is

applicable to certain Gates Learjet

Model 35 and 36 series airplanes that

have been modified in accordance with

Raisbeck Supplemental Type Certificate

(STC) SA766NW. That AD requires the

accomplishment of one of two optional

actions, both of which are intended to

prevent the airplane from encountering

the potentially hazardous condition of

aileron buffet or buzz:

1. One optional action requires

operators to reduce permanently the

maximum operating Mach limit (MMO)

of these airplanes from .83 to .80. This

action includes resetting the Mach
Federal Register / Vol. 61, No. 93 / Monday, May 13, 1996 / Proposed Rules 21983

overspeed warning switch; recalibrating

the airspeed indicator; and changing the

FAA-approved Airplane Flight Manual

(AFM) Supplement to reflect the new

Mach limit.

2. The other optional action requires

operators to remove the Raisbeck STC

modifications and to return the airplane

either to its original configuration or to

the Gates Learjet ‘‘Softflight’’

configuration.

AD 85–16–04 was prompted by

several reports of incidents in which

Learjet Model 35 and 36 series airplanes

modified with the Raisbeck STC

experienced aileron buffet or buzz

during cruise. These incidents of aileron

instability occurred on airplanes

operating at high gross weights when

they were flying above 42,000 feet at

Mach .80 to .83. Aileron buffet or buzz,

if it is of a certain severity, can result

in an unacceptable deterioration in the

lateral control characteristics of the

airplane.

Actions Subsequent to the Issuance of

AD 85–16–04

When AD 85–16–04 was issued, its

applicability included only certain

modified airplanes, which were

identified by specific serial numbers.

However, since the issuance of that AD,

the FAA has received a report that at

least one additional airplane, that was

not included in the applicability of the

AD, has been modified in accordance

with the subject Raisbeck STC. (The

STC installed on this particular airplane

was performed at a non-U.S. repair

station.) In light of this, that airplane

may be subject to the same unsafe

condition addressed by AD 85–16–04.

Further, since the Raisbeck STC could

be installed on Model 35 or 36 series

airplanes anywhere in the world, the

FAA may not be immediately aware of

it. Therefore, the FAA has determined

that any of these airplanes on which the

Raisbeck STC is installed could be

subject to that same unsafe condition.

Description of the Proposed AD

Since an unsafe condition has been

identified that is likely to exist or

develop on other products of this same

type design, the proposed AD would

require the accomplishment of one of

two optional actions, both of which are

intended to prevent the airplane from

encountering the potentially hazardous

condition of aileron buffet or buzz:

1. Permanently reducing the

maximum operating MMO from .83 to

.80; resetting the Mach overspeed

warning switch; recalibrating the

airspeed indicator; and changing the

FAA-approved Airplane Flight Manual

(AFM) Supplement to reflect the new

Mach limit; or

2. Removing the Raisbeck STC

modifications and returning the airplane

either to its original configuration or to

the Gates Learjet ‘‘Softflight’’

configuration.

These proposed requirements are the

same actions currently required by AD

85–16–06.

The applicability of the proposed AD

would include all Learjet Model 35 and

36 series airplanes modified in

accordance with Raisbeck STC

SA766NW that are not currently subject

to AD 85–16–04.

[Note: The FAA’s normal policy is that when

an AD requires a substantive change, such as

a change (expansion) in its applicability, the

‘‘old’’ AD is superseded by removing it from

the system and a new AD is added. In the

case of this proposed AD action, the FAA

normally would have proposed superseding

AD 85–16–04 to expand its applicability to

include the additional affected airplanes.

However, in reconsideration of the entire

fleet size that would be affected by a

supersedure action, and the consequent

workload associated with revising

maintenance record entries, the FAA has

determined that a less burdensome approach

is to issue a separate AD applicable only to

these additional airplanes. This proposed AD

would not supersede AD 85–16–04; airplanes

listed in the applicability of AD 85–16–04 are

required to continue to comply with the

requirements of that AD. This proposed AD

is a separate AD action, and is applicable

only to airplanes that are not subject to AD

85–16–04.]

Petitioning for an Exemption of the

Requirements of the Final Rule

Affected operators should note that

the aileron instability that is the subject

of this proposed AD is a condition

affected by the contour of the wing

leading edge, which is a function of

manufacturing tolerances. In light of

this, the FAA recognizes that not all

airplanes modified in accordance with

Raisbeck STC SA766NW may exhibit

the problem of aileron buffet or buzz

below .83 Mach. Should this proposal

become a final rule, operators of those

airplanes may wish to petition the FAA

for an exemption from the requirements

of the rule, under the provisions of part

11 of the Federal Aviation Regulations

(14 CFR 11), ‘‘General Rulemaking

Procedures.’’

Petitioners for such an exemption

should provide data that would justify

a grant of exemption, including, but not

limited to, information concerning the

number of flights the airplane has flown

in conditions involving high weight,

high altitude, and high speed, and if any

incident of buffet or buzz was observed

during flight in those conditions. Based

on the data submitted with the petition,

the FAA will determine on a case-bycase basis if a flight evaluation or other

additional data are necessary to

determine if granting the petition (1)

would not adversely affect safety, and

(2) would be in the public interest.

Cost Impact

There are approximately 29 Gates

Learjet Model 35 and 36 series airplanes

of the affected design in the worldwide

fleet. The FAA estimates that at least 1

airplane of U.S. registry would be

affected by this proposed AD.

To accomplish the removal and

recalibration of the airspeed indicators

and Mach overspeed warning switch,

and to revise the AFM Supplement, as

would be required by ‘‘Option I’’ of the

proposed rule, it would take

approximately 5 work hours per

airplane, at an average labor rate of $60

per work hour. The FAA estimates that

it would cost approximately $1,000 per

airplane to reset the airspeed indicators

and Mach overspeed warning switch.

Based on these figures, the cost impact

of this action of the proposed AD on

U.S. operators is estimated to be $1,300

per airplane.

To accomplish the removal of the STC

modifications, as would be required by

‘‘Option II’’ of the proposed rule, it

would take approximately 100 work

hours per airplane, at an average labor

rate of $60 per work hour. Based on

these figures, the cost impact of this

action of the proposed AD on U.S.

operators is estimated to be $6,000 per

airplane.

The cost impact figures discussed

above are 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
21984 Federal Register / Vol. 61, No. 93 / Monday, May 13, 1996 / Proposed Rules

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.

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

Gates Learjet: Docket 96–NM–63–AD.

Applicability: Model 35, 35A, 36 and 36A

series airplanes, modified in accordance with

Raisbeck Group Supplemental type

Certificate (STC) SA766NW, that do not have

one of the serial numbers listed in Table 1

of this AD; certificated in any category.

TABLE 1

[Serial Numbers * NOT affected by this AD]

35–023 35A–092 35A–192 36–004

35–034 35A–093 35A–203 36–017

35–042 35A–095 35A–206 36–028

35–044 35A–118 35A–207 36A–029

35–047 35A–127 35A–209 36A–031

35A–068 35A–132 35A–228 36A–038

35A–073 35A–135 35A–231 36A–043

35A–075 35A–145 35A–244 36A–044

35A–076 35A–172 35A–245

35A–086 35A–185 36–003

*Airplanes having the serial numbers listed

in Table 1 are subject to similar requirements

mandated by AD 85–16–04, amendment 39–

5110.

Note 1: This AD applies to each airplane

as indicated in the preceding applicability

provision, regardless of whether it has been

otherwise modified, altered, or repaired in

the area subject to the requirements of this

AD. For airplanes that have been modified,

altered, or repaired so that the performance

of the requirements of this AD is affected, the

owner/operator must request approval for an

alternative method of compliance in

accordance with paragraph (b) of this AD.

The request should include an assessment of

the effect of the modification, alteration, or

repair on the unsafe condition addressed by

this AD; and, if the unsafe condition has not

been eliminated, the request should include

specific proposed actions to address it.

Compliance: Required as indicated, unless

accomplished previously.

To prevent deterioration of the airplane’s

lateral control characteristics as a result of

aileron buffet or buzz, accomplish the

following:

(a) Within 200 hours time-in-service after

the effective date of this AD, or within 6

months after the effective date of this AD,

whichever occurs first, accomplish either

paragraph (a)(1) or (a)(2) of this AD:

(1) Option I. Permanently reduce the

airplane’s maximum operating Mach limit

(MMO) by accomplishing the actions specified

in paragraphs (a)(1)(i), (a)(1)(ii), and (a)(1)(iii)

of this AD:

(i) Submit the FAA-approved STC

SA766NW Airplane flight Manual

Supplement to the Manager, Flight Test

Branch, ANM–160S, Seattle Aircraft

Certification Office, FAA, Transport Airplane

Directorate, 1601 Lind Avenue SW., Renton,

Washington 98055–4056; to change the limit

Mach number from .83 to .80. And

(ii) Remove the ‘‘Mach Overspeed Warning

Switch’’ and have it reset from Mach .83 to

.80. Contact the manufacturer, PRECISION

SENSOR, P.O. Box 509, Milford, Connecticut

06460; telephone number (203) 877–2795; to

have the instrument recalibrated. Reidentify

the Mach overspeed warning switch by inkstamping the words ‘‘Mach limit .80’’

adjacent to the part number. Reinstall the

‘‘Mach Overspeed Warning Switch’’ after it

has been so recalibrated. And

(iii) Remove the pilot’s and copilot’s

airspeed indicators and have them modified

by changing the ‘‘barber pole’’ from Mach

number .83 to .80. The instrument must be

recalibrated by the instrument manufacturer

or a certified repair station. Reidentify the

airspeed indicators by ink stamping ‘‘Mach

limit .80’’ adjacent to the part number.

Reinstall the pilot’s and copilot’s airspeed

indicators after they have been so modified.

(2) Option II. Remove the modifications

installed in accordance with Raisbeck Group

STC SA766NW, and return the aircraft either

to the original type design configuration, or

to the Gates Learjet ‘‘Softflight’’

configuration.

(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, Seattle

Aircraft Certification Office (ACO), FAA,

Transport Airplane Directorate. Operators

shall submit their requests through an

appropriate FAA Principal Maintenance

Inspector, who may add comments and then

send it to the Manager, Seattle ACO.

Note 2: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Seattle 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 May 7,

1996.

Darrell M. Pederson,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 96–11881 Filed 5–10–96; 8:45 am]

BILLING CODE 4910–13–P

14 CFR Part 71

[Airspace Docket No. 96–ACE–5]

Proposed Amendment to Class E

Airspace; Ames, IA

AGENCY: Federal Aviation

Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking.

SUMMARY: This notice proposes to

amend the Class E airspace area at

Ames, Iowa. The development of a new

Standard Instrument Approach

Procedure (SIAP) based on the Global

Positioning System (GPS) has made the

proposal necessary. The intended effect

of this proposal is to provide additional

controlled airspace for aircraft executing

the SIAP at the above listed airport.

DATES: Comments must be received on

or before June 20, 1996.

ADDRESSES: Send comments on the

proposal in triplicate to: Manager,

Operations Branch, ACE–530, Federal

Aviation Administration, Docket No.

96–ACE–5, 601 East 12th Street, Kansas

City, MO 64106.

The official docket may be examined

in the Office of the Assistant Chief

Counsel for the Central Region at the

same address between 9:00 a.m. and

3:00 p.m., Monday through Friday,

except Federal holidays.

An informal docket may also be

examined during normal business hours

in the office of the Manager, Operations

Branch, Air Traffic Division, at the

address listed above.

FOR FURTHER INFORMATION CONTACT:

Kathy Randolph, Air Traffic Division,

Operations Branch, ACE–530C, Federal

Aviation Administration, 601 East 12th

Street, Kansas City, Missouri 64106;

telephone number: (816) 426–3408.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested parties are invited to

participate in this proposed rulemaking

by submitting such written data, views,

or arguments as they may desire.

Comments that provide the factual basis

supporting the views and suggestions

presented are particularly helpful in

developing reasoned regulatory

decisions on the proposal. Comments