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Federal Register / Vol. 86, No. 87 / Friday, May 7, 2021 / Proposed Rules 11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https www.regulations.gov. Follow the instructions for submitting comments.
Fax: 202 4932251.
Mail: U.S. Department of Transportation, Docket Operations, M
30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9 a.m. and 5
p.m., Monday through Friday, except Federal holidays.
For service information identified in this NPRM, contact Gulfstream Aerospace Corporation, Technical Publications Dept., P.O. Box 2206, Savannah, GA 31402; phone: 800 810
4853; email: pubs@gulfstream.com;
website: https www.gulfstream.com/
en/customer-support/. You may view this service information at the Airworthiness Products Section, Operational Safety Branch, 901 Locust, Kansas City, MO 64106. For information on the availability of this material at the FAA, call 816 3294148.
Examining the AD Docket You may examine the AD docket at https www.regulations.gov by searching for and locating Docket No.
FAA20210156; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this NPRM, any comments received, and other information. The street address for Docket Operations is listed above.
FOR FURTHER INFORMATION CONTACT: Jeff Johnson, Aviation Safety Engineer, Atlanta ACO Branch, FAA, 1701
Columbia Ave., College Park, GA 30337;
phone: 404 4745554; fax: 404 474
5606; email: jeffrey.d.johnson@faa.gov.
SUPPLEMENTARY INFORMATION:
Comments Invited The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under ADDRESSES. Include Docket No.
FAA20210156; Project Identifier AD
202001594T at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend this proposal because of those comments.
Except for Confidential Business Information CBI as described in the following paragraph, and other
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information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to https
www.regulations.gov, including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.
Confidential Business Information CBI is commercial or financial information that is both customarily and actually treated as private by its owner.
Under the Freedom of Information Act FOIA 5 U.S.C. 552, CBI is exempt from public disclosure. If your comments responsive to this NPRM
contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI
as PROPIN. The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI
should be sent to Jeff Johnson, Aviation Safety Engineer, Atlanta ACO Branch, FAA, 1701 Columbia Ave., College Park, GA 30337. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.
Background During flight testing of a Gulfstream Model GVIIG500 airplane, when the aircraft was configuring for a steep approach test point, the crew received a flap failure message. After landing, inspection revealed that the left-hand flap track B yoke had become disconnected due to structural failure.
Gulfstreams investigation to determine the root cause of the failure revealed that the flap yoke fittings for certain serial-numbered Gulfstream Model GVIIG500 airplanes have design features that cause decreased fatigue life. The unsafe design features include insufficient shaft diameter, a small fillet radius detail at the top of the shaft, and a rough surface finish allowance, which collectively attribute to a potential yoke fitting failure. These design features ultimately cause higher stress concentrations leading to premature and fast-fracture overload of the flap actuator yoke at the junction of the fitting shaft and yoke clevis.
This condition, if not addressed, could result in failure of the flap yoke fitting during flap transition, which could cause the flaps to stop moving.
This, combined with additional failures
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in the flap actuator force limiter or flap yoke actuator disconnect, could result in asymmetric flap positions, leading to a loss of airplane control.
FAAs Determination The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.
Related Service Information Under 1
CFR Part 51
The FAA reviewed Gulfstream GVII
G500 Aircraft Service Change No. 032, Initial Issue, dated November 20, 2020
Gulfstream ASC No. 032. This service information specifies procedures for replacing the flap inboard and outboard yoke fitting assemblies and upper bushings. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in ADDRESSES.
Other Related Service Information The FAA also reviewed Gulfstream GVII500 Customer Bulletin No. 045, Initial Issue, dated November 20, 2020.
This service information specifies the compliance time and additional information for Gulfstream ASC No.
032. The FAA also reviewed Gulfstream Aerospace GVIIG500 Aircraft Maintenance Manual AMM Document Number GACACGVIIG500AMM
0001, Revision 7, dated December 15, 2020. This document contains revised airworthiness limitations, maintenance checks, and inspections.
Proposed AD Requirements in This NPRM
This proposed AD would require replacing the flap inboard and outboard yoke fitting assemblies and updating chapter 5 of your existing AMM to incorporate a 20,000 flight cycle life limit.
Differences Between This Proposed AD
and the Service Information Gulfstream ASC No. 032 contains actions labeled Required for Compliance RC, and the language in the ASC and in paragraph h3 of this AD indicates that operators must comply with all actions labeled RC for compliance with this AD. However, this AD does not require all of the steps in Gulfstream ASC No. 032 that are labeled as RC. Operators only need to comply with the RC steps specified in paragraph g of this AD.

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