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###### Department of Transportation

###### Federal Aviation Administration 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed advisory circular revision and request for comments.

# SUMMARY:

                        The Federal Aviation Administration requests comments regarding a proposed revision to Advisory Circular (AC) 25-7A, “Flight Test Guide for Certification of Transport Category Airplanes.” The proposed revision provides revised guidance concerning proposed rulemaking published elsewhere in this issue of the                         **Federal Register**                         concerning the airspeed indicating system. This notice provides interested persons an opportunity to comment on the proposed revision to the AC concurrently with the proposed rulemaking.                     

# DATES:

Comments must be received on or before July 16, 2001. 

# ADDRESSES:

Send all comments on the proposed AC revision to the Federal Aviation Administration, Attention: Don Stimson, Airplane & Flight Crew Interface Branch, ANM-111, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Ave SW., Renton, WA 98055-4056. Comments may be examined at the above address between 7:30 a.m. and 4 p.m. weekdays, except Federal holidays. 

# FOR FURTHER INFORMATION CONTACT:

Patricia Siegrist, Program Management Branch, ANM-114, at the above address, telephone (425) 227-2126, or facsimile (425) 227-1320. 

# SUPPLEMENTARY INFORMATION:

## Comments Invited 

                    You are invited to comment on the proposed revision to the AC by submitting written data, views, or                           ( print page 26906)                        arguments. You must identify the title of the AC and submit comments in duplicate to the address specified above. The Transport Airplane Directorate will consider all comments received on or before the closing date for comments before issuing a revision to the AC.                 

## Discussion 

                    By a notice of proposed rulemaking published in this same issue of the                     **Federal Register**                    , the Federal Aviation Administration (FAA) proposes to amend the airworthiness standards for transport category airplanes concerning the airspeed indicating system. The proposed amendment would update the current standards by adding airspeed indication requirements for speeds greater than and less than the speed range for which airspeed indication accuracy requirements currently apply, would add a requirement that airspeed indications not cause the pilot undue difficulty between the initiation of rotation and the achievement of a steady climbing condition during takeoff, and would also add a requirement to limit the effects of airspeed lag. The proposed amendment would harmonize these standards with those being proposed for the European Joint Aviation Requirements (JAR-25).                 

To address the additional rulemaking requirements proposed for part 25, the FAA also proposes to revise Advisory Circular (AC) 25-7A to describe acceptable means of showing compliance with the proposed rule. This revision only addresses guidance material associated with the airspeed indicating system, and should not be confused with other proposed revisions of AC 25-7A for which the FAA is currently seeking comment. Issuance of a revised AC is contingent on adoption of the proposed revisions to part 25. 

## Proposed Revisions to AC 25-7A 

1. Replace existing paragraph 177a(1)(v) with new paragraphs a(1)(v) and (vi) to read as follows: 

                    (v) An acceptable means of compliance when demonstrating a perceptible speed change between 1.3 VS                     to stall warning speed is for the rate of change of IAS with CAS to be not less than 0.75.                 

                    (vi) An acceptable means of compliance when demonstrating a perceptible speed change between VMO                     to VMO                    +                    2/3                     (VDF                    −VMO) is for the rate of change of IAS with CAS to be not less than 0.50.                 

2. Redesignate existing paragraph 177a(1)(v), Airspeed Lag, as paragraph 177a(1)(vii). 

Issued in Renton, Washington, on May 2, 2001. 

Lirio L. Nelson, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 01-12104 Filed 5-14-01; 8:45 am] 

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