Document Headings

                    Document headings vary by document type but may contain                    the following:                  
                -                       the agency or agencies that issued and signed a document                    
                -                       the number of the CFR title and the number of each part                      the document amends, proposes to amend, or is directly                      related to                    
                -                       the agency docket number / agency internal file number                    
                -                       the RIN which identifies each regulatory action listed in                      the Unified Agenda of Federal Regulatory and Deregulatory                      Actions                    

                    See the                                          Document Drafting Handbook                                        for more details.                  

###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [FAA Docket No. FAA-2020-0994; Project Identifier AD-2020-00687-T]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Proposed rule; withdrawal.

# SUMMARY:

The FAA is withdrawing a notice of proposed rulemaking (NPRM) that proposed to adopt a new airworthiness directive (AD) for certain Gulfstream Aerospace Corporation (Gulfstream) Model GVII-G600 airplanes. The NPRM was prompted by a report that a failure mode in the data concentration network (DCN) software causes the pitch attitude value to freeze on the primary flight display (PFD) for up to 20 seconds. The NPRM proposed to require updating the DCN and flight deck master operating system (MOS) software. Since issuance of the NPRM, the FAA has determined that there is not an unsafe condition because all affected airplanes have updated software. Accordingly, the NPRM is withdrawn.

# DATES:

                         As of June 8, 2021, the proposed rule, which published in the                         **Federal Register**                         on February 23, 2021 (86 FR 10875), is withdrawn.                    

# ADDRESSES:

 

## Examining the AD Docket

                    You may examine the AD docket at                     *https://www.regulations.gov*                     by searching for and locating Docket No. FAA-2020-0994; 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 AD action, the regulatory evaluation, any comments received, and other information. The street address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.                

# FOR FURTHER INFORMATION CONTACT:

                        Myles Jalalian, Aviation Safety Engineer, Atlanta ACO Branch, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (404) 474-5572; fax: (404) 474-5606; email:                         *myles.jalalian@faa.gov.*

# SUPPLEMENTARY INFORMATION:

## Background

                    The FAA issued an NPRM that proposed to amend 14 CFR part 39 by adding an AD that would apply to certain serial-numbered Gulfstream Model GVII-G600 airplanes. The NPRM published in the                     **Federal Register**                     on February 23, 2021 (86 FR 10875). The NPRM was prompted by a report of a failure mode in the DCN software that causes pitch attitude value to freeze on the PFD for up to 20 seconds, which results in temporarily incorrect pitch indications.                

The effect is evident only if the pitch of the airplane changes during the 20 second reset window. After 20 seconds, the system returns to normal. The standby flight display and heads up display are unaffected by this failure mode and continue to display the correct pitch attitude. However, there is not an alert or annunciation that informs the flight crew of a stale (frozen) pitch display or potentially misleading flight information.

The NPRM proposed to require installing the MOS software update part number EB60001034-0106, updating the DCN software level to version 10.10.12 in support of the MOS software update, and operationally checking the installations. Incorrect pitch indications could result in the loss of control of the airplane during certain phases of flight during instrument meteorological conditions.

## Actions Since the NPRM Was Issued

                    After issuance of the NPRM, the FAA received a comment from Gulfstream recommending the FAA withdraw the NPRM based on full fleet compliance. All Gulfstream Model GVII-G600 airplanes have corrected the unsafe condition by complying with the proposed software update. The FAA has determined that the unsafe condition has been removed from the fleet. In addition, since Gulfstream controls the software, it is unlikely the unsafe condition will be re-introduced.                          ( print page 30399)    

Based on the above information, the FAA has determined that AD action is not warranted and the proposal should be withdrawn.

Withdrawal of the NPRM constitutes only such action and does not preclude the FAA from further rulemaking on this issue, nor does it commit the FAA to any course of action in the future.

## Regulatory Findings

Since this action only withdraws an NPRM, it is neither a proposed AD nor a final rule. This action, therefore, is not covered under Executive Order 12866 or the Regulatory Flexibility Act.

# List of Subjects in 14 CFR Part 39

      - Air transportation
      - Aircraft
      - Aviation safety
      - Incorporation by reference
      - Safety

## The Withdrawal

                    Accordingly, the notice of proposed rulemaking, which published in the                     **Federal Register**                     on February 23, 2021 (86 FR 10875), is withdrawn.                

Issued on May 28, 2021.

Lance T. Gant, 

Director, Compliance & Airworthiness Division, Aircraft Certification Service.

[FR Doc. 2021-11813 Filed 6-7-21; 8:45 am]

BILLING CODE 4910-13-P