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 
          - [Docket No. 99-NM-138-AD; Amendment 39-11735; AD 2000-10-11] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT.

# ACTION:

Final rule. 

# SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to certain Gulfstream Model G-159 series airplanes, that requires an inspection to determine the type of pneumatic deicing boots, and an Airplane Flight Manual (AFM) revision only for those airplanes equipped with “modern” boots. This amendment is 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 this 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. 

# EFFECTIVE DATE:

June 26, 2000. 

# ADDRESSES:

Information pertaining to this amendment may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 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:

                    A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to Gulfstream Model G-159 series airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the                     **Federal Register**                     on November 18, 1999 (64 FR 62991). That action proposed to require                           ( print page 32012)                        an inspection to determine the type of pneumatic deicing boots, and an airplane flight manual (AFM) change only for those airplanes equipped with “modern” boots.                

## Since the Issuance of the NPRM 

The FAA has received information indicating that natural ice shedding, melting, or sublimation from the protected areas of the pneumatic deicing boot system of the wing and tail leading edge will eliminate most residual ice. In light of that information, the FAA has determined that a revision of the last bulleted paragraph of the airplane flight manual revision specified in paragraph (a) of the NPRM is necessary. Consequently, that paragraph has been revised from, “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,” to delete the phrase, “and after the airplane is determined to be clear of ice.”

## Comments

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

## Request to Add Further Requirements

The commenter, the United Kingdom Civil Aviation Authority, requests that the statement in the supplemental notice of proposed rulemaking (NPRM) advising that a potential for adverse aerodynamic effects of ice adhering to the airplane exists should be addressed in more detail. The commenter explains that icing boots contaminated with dirt or in a deteriorated condition can induce such ice adhering to the airplane. The commenter points out that various cleaning and protection fluids are available that provide extended life to the deicing boots, protection of the boots against ultraviolet (UV) rays, and assistance in maintaining the boots in a clean condition. However, the commenter notes that not all maintenance programs schedule tasks effectively for the use of such cleaning and protection fluids. Therefore, the commenter requests that the FAA consider mandating a specific schedule to use such cleaning and protection products. The commenter states that such a required schedule should be required for airplanes equipped with either the “modern” or “older” boots.

The FAA does not concur with the commenter's requests. The FAA considers that normal wear and tear on the deicing boot materials is to be expected, and that the adhesion characteristics of the boot increases as the boot surface degrades over time. Operators have the responsibility to monitor the performance of the deicing boots installed on their airplanes, and to perform maintenance as required. 

                    The FAA acknowledges that use of certain ice-phobic chemicals may provide an additional safety benefit. However, a variety of factors (                    *e.g.,*                     normal wear and tear, “patching,” and oxidation of boot material) exist in varying degrees on individual airplanes. As a result, the optimum frequency of application will vary during the life of the boot. The FAA has received no quantitative data to demonstrate the adequacy of particular amounts of ice-phobic chemical sprays or to provide adequate intervals of application. Therefore, the FAA cannot establish an appropriate application interval at this time. However, if additional data becomes available, the FAA may consider further rulemaking.                

## Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

## Cost Impact

The FAA estimates that 141 airplanes of U.S. registry will be affected by this AD. 

The FAA estimates that it will take approximately 2 work hours per airplane to accomplish the AFM revision, at the average labor rate of $60 per work hour. Based on these figures, the cost impact of the 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 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 adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.

                    For the reasons discussed above, I certify that this action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from 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

## Adoption of the Amendment 

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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 

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

**2000-10-11 Gulfstream Aerospace Corporation**                             (Formerly Grumman): Amendment 39-11735. Docket 99-NM-138-AD.                        

*Applicability:*                             Model G-159 series airplanes equipped with pneumatic deicing boots, certificated in any category.                        

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.)
      ( print page 32013)    
(a) Within 10 days after the effective date of this AD: Perform a visual inspection to determine if the types 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.”

(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.

(d) This amendment becomes effective on June 26, 2000.

Issued in Renton, Washington, on May 15, 2000. 

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 00-12672 Filed 5-19-00; 8:45 am] 

BILLING CODE 4910-13-U