[Federal Register Volume 62, Number 249 (Tuesday, December 30, 1997)]
[Rules and Regulations]
[Pages 67708-67711]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-33512]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-17-AD; Amendment 39-10263; AD 97-26-20]
RIN 2120-AA64


Airworthiness Directives; Aviat Aircraft Inc. Models S-2A, S-2B, 
and S-2S Airplanes (formerly Pitts Models S-2A, S-2B, and S-2S 
airplanes)

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes Airworthiness Directive AD 96-09-08 
R1, which applies to Aviat Aircraft Inc. (Aviat) Models S-2A, S-2B, and 
S-2S airplanes (formerly Pitts Models S-2A, S-2B, and S-2S), and 
currently requires repetitively inspecting the upper longerons just aft 
of the rear cabane struts for cracks and repairing any cracks. This 
action retains the same actions as the current AD; lengthens the time 
interval between repetitive inspections; requires either installing a 
marked accelerometer in order to continue to perform acrobatic 
maneuvers and installing a placard that specifies gravity (``g'') force 
limitations, or installing a placard prohibiting acrobatic maneuvers; 
and, requires inserting revisions into the Airplane Flight Manual 
(AFM). This action is the result of reports of cracking in the upper 
longerons caused by operating the airplane outside of the certificated 
design limits and the availability of a design modification that, when 
incorporated, repairs the damaged upper longeron area. The actions 
specified by this AD are intended to prevent cracking and subsequent 
failure of the longerons with consequent loss of control of the 
airplane.

DATES: Effective January 22, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 22, 1998.

ADDRESSES: Service information that applies to this AD may be obtained 
from Aviat Aircraft Inc., P. O. Box 1240, 672 South Washington Street, 
Afton, Wyoming, 83110; telephone (307) 886-3151; facsimile (307) 886-
9674. This information may also be examined at the Federal Aviation 
Administration (FAA), Central Region, Office of the Regional Counsel, 
Attention: Rules Docket 97-CE-17-AD, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106; or at the Office of the Federal Register, 
800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Roger Caldwell, Project Engineer, FAA, 
Denver Aircraft Certification Office, 26805 East 68th Ave., Room 214, 
Denver, Colorado 80216; telephone (303) 342-1086; facsimile (303) 342-
1088.

SUPPLEMENTARY INFORMATION:

Events Leading to the Issuance of This AD

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to supersede AD 96-09-08 R1, Amendment 39-9690 (61 FR 
35936, No. 132, July 9, 1996), that applies to Aviat Models S-2A, S-2B, 
and S-2S airplanes (formerly Pitts Models S-2A, S-2B, and S-2S), was 
published in the Federal Register on May 30, 1997 (62 FR 29309). AD 96-
09-08 R1 currently requires repetitively inspecting the longerons 
around the rear cabane struts for cracks on Aviat Models S-2A (all 
serial numbers (S/N)), S-2B (S/N 5000 through 5350), and S-2S (all S/
N), and repairing and reinforcing any crack found during the 
inspections. The proposed AD would supersede AD 96-09-08 R1 with a new 
AD that would require:
    (1) Repetitively inspecting the upper longerons aft of the rear 
cabane struts

[[Page 67709]]

and forward of the instrument panel for cracks;
    (2) Modifying any cracked longeron found during any inspection 
required by the proposed AD by incorporating Aviat Kit No. S-2-513;
    (3) Inserting the revisions referenced in the Aviat SB No. 24, 
Date: March 20, 1996, Revised: November 22, 1996 into the AFM; and
    (4) Accomplishing one of the following:

--Installing a redlined accelerometer marked at the +6g and -3g hash 
marks indicating the acrobatic ``g'' force limitations and a placard 
(part number 2-7604-47) stating the ``g'' force limitations; or
--Fabricating and installing a placard in the pilot's clear view using 
at least \1/8\-inch letters that incorporate the words:
``ACROBATIC MANEUVERS PROHIBITED.''
    Accomplishment of this action would be in accordance with the Aviat 
Aircraft Inc. Service Bulletin No. 24, Date: March 20, 1996; Revised: 
November 22, 1996, and Aviat Aircraft Inc. Installation Instructions to 
Kit No. S-2-513, dated August 26, 1996; Revised May 9, 1997.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Several comments were received on the 
proposed rule. Due consideration has been given to the following 
comments.
    A commenter suggested that the Aviat Pitts Model S-2A be eliminated 
from the applicability of the action because the aircraft does not have 
enough horsepower to sustain airspeeds that will damage the airframe 
structure.
    The FAA does not concur. The FAA is obligated to address the whole 
fleet (all models) since it is possible to exceed the fatigue limits on 
all models regardless of horsepower. The aircraft weight and maneuver 
entry speed is the factor that drives the resultant gravity (``g'') 
load. All of the Aviat models addressed can enter a snap roll while in 
a dive with the airspeed higher than the recommended entry speed. The 
final rule will not be changed as a result of this comment.
    A commenter wanted the FAA to withdraw the NPRM because no fleet-
wide problem exists.
    The FAA does not concur. The reason this action was taken is 
because of four known incidents where cracked longerons were the cause. 
After additional investigation, tests showed that exceeding the ``g'' 
force limitations causes stress to the longerons, thus producing 
cracks. Therefore, the FAA is requiring additional measures to assure 
that the operation of the affected airplanes does not exceed the 
certification limits. The FAA also wants to assure that the affected 
airplanes are flying without cracks. If the upper longerons are not 
repetitively inspected for cracks, then the airplane is susceptible to 
an unsafe condition. The final rule will not be changed as a result of 
this comment.
    One commenter suggested that the frequency of the longeron 
inspection occur at every 100-hour time-in-service (TIS) intervals.
    The FAA concurs and notes that a 100 hour TIS interval for 
repetitive inspections of the upper longeron area was proposed in the 
NPRM. The final rule will not be changed as a result of this comment.
    A commenter wants the ``g'' limitation placard to read ``+4.5g and 
-2.5g while performing a snap roll maneuver'' because the twisting 
forces imposed on the airframe by snap rolls are more likely to cause 
structural failure than straight positive ``g'' force.
    The FAA does not concur. There has been no convincing analysis to 
indicate that anything less than the original certificated maximum 
``g'' force levels of +6 and -3 should not be the airplane operating 
limits. The final rule will not be changed as a result of this comment.
    Another commenter suggested inspecting the fuselage for structural 
damage if a ``g'' factor of +6 is exceeded during landing. The 
commenter did not provide any justification to support this argument. 
As a result, this comment will not change the final rule.
    One commenter wanted a requirement to mark the accelerometers at 
the operating limitations. The FAA agrees. This requirement was 
proposed in the NPRM. The final rule will not change as a result of 
this comment.
    A commenter suggested delaying the final rule pending further study 
of the effect of snap roll maneuvers because the AD does not recognize 
or discuss the twisting forces imposed on the airframe by snap rolling 
maneuvers, and that the snap roll maneuvers result in a higher ``g'' 
force than straight positive ``g'' forces.
    The FAA does not concur. Flight test analysis shows that the 
original operating limits that were determined during certification of 
these airplanes are adequate as long as the operator flies the airplane 
within the ``g'' force limits. The final rule will not change as a 
result of this comment.
    Another comment requested that the FAA delete the requirement for 
the placard on the accelerometer. No justification was presented for 
this request. The FAA has determined that this placard is necessary to 
fully address the unsafe condition. The final rule will not change as a 
result of this comment.
    One comment recommended amending the aircraft documents to reflect 
a mandatory VNE (never exceed speed) for snap roll maneuvers to limit 
the ``g'' force loads. The commenter presented no justification for 
this recommendation.
    The FAA does not concur. This recommendation offers no benefit over 
the already proposed placard placed near the accelerometer because the 
flight manual already states the certificated operating ``g'' limits 
and entry speeds for maneuvers.
    Aviat Aircraft Inc. commented that they agree with the need for the 
AD, but Aviat felt that the general theme of the preamble to the NPRM 
was degrading and made hostile references to the Aviat airplanes. Aviat 
submitted a re-written preamble to NPRM. The FAA did not re-print this 
submission as part of the final rule comments because the comments made 
did not speak to the AD only to the discussion in the preamble of the 
NPRM. The preamble to the NPRM is not published as part of the final 
rule. Therefore, this final rule is not changed as a result of this 
comment. The document submitted can be obtained by written request to 
the Office of the Regional Counsel's Rules Docket found in the 
ADDRESSES section of this AD.

The FAA's Determination

    After careful review of all available information related to the 
subject presented above, the FAA has determined that air safety and the 
public interest require the adoption of the rule as proposed except for 
minor editorial corrections. The FAA has determined that these minor 
corrections will not change the meaning of the AD and will not add any 
additional burden upon the public than was already proposed.

Cost Impact

    The FAA estimates that 500 airplanes in the U.S. registry will be 
affected by this AD, that it will take approximately 8 workhours per 
airplane to accomplish the initial inspection and modification, and 
that the average labor rate is approximately $60 an hour. The 
installation of the revisions to the AFM and the placard may be 
performed by the owner/operator holding at least a private pilot 
certificate as authorized by Secs. 43.7 and 43.9 of the Federal 
Aviation Regulations (14 CFR 43.7 and 43.9). Therefore, the only labor 
cost associated with this step is the time of the owner/

[[Page 67710]]

operator. Parts costs are estimated to be approximately $400 for Aviat 
Kit No. S-2-513 and $10 for the placard. Based on these figures, the 
total cost impact of this AD on U.S. operators is estimated to be 
$445,000 or $890 per airplane. The estimated cost does not account for 
the repetitive inspections because the FAA has no way to determine the 
number of repetitive inspections that might be incurred over the life 
of the airplane. The manufacturer has informed the FAA that they have 
distributed kits to reinforce 4 airplanes. With this in mind, the 
approximate cost for this AD on U.S. operators will be reduced from 
$445,000 to $441,440.

Regulatory Impact

    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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 copy of the final 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, Incorporation by 
reference, 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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing airworthiness directive 
(AD) 96-09-08 R1, Amendment No. 39-9690 and by adding a new AD to read 
as follows:

97-26-20 Aviat Aircraft Inc.: Amendment No. 39-10263; Docket No. 97-
CE-17-AD; Supersedes AD 96-09-08 R1, Amendment 39-9690.

    Applicability: Models S-2A (all serial numbers (S/N)), S-2B (S/N 
5000 through 5350), and S-2S (all serial numbers) airplanes 
(formerly Pitts Models S-2A, S-2B, and S-2S), certificated in any 
category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 (f) 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 in the body of this AD, unless 
already accomplished.
    To prevent cracking and subsequent failure of the longerons with 
consequent loss of control of the airplane, accomplish the 
following:
    (a) At the accumulation of 300 hours total time-in-service (TIS) 
or within the next 25 hours TIS after the effective date of this AD, 
whichever occurs later, and thereafter at intervals not to exceed 
100 hours TIS, inspect (using a 10x magnifying glass) the longerons 
aft of the rear cabane strut and forward of the instrument panel for 
cracks in accordance with paragraphs A. 1. through A. 4. and Figure 
1 in the ACCOMPLISHMENT INSTRUCTIONS of Aviat Aircraft Inc. (Aviat) 
Service Bulletin (SB) No. 24, Date: March 20, 1996, Revised: 
November 22, 1996.
    (1) Disregard the instructions in paragraph A. 5. in the 
ACCOMPLISHMENT INSTRUCTIONS of Aviat SB No. 24, Date: March 20, 
1996, Revised: November 22, 1996. This AD takes precedence over the 
instructions in paragraph A. 5 referenced above.
    (2) If cracks are found during any inspection required by this 
AD, prior to further flight, modify the cracked area by 
incorporating Aviat Kit No. S-2-513 in accordance with the 
INSTALLATION INSTRUCTIONS section in Aviat Kit No. S-2-513, dated 
August 26, 1996, Revised: May 9, 1997.
    (3) The modification does not eliminate the 100-hour TIS 
interval repetitive inspections.
    (b) At the accumulation of 300 hours total TIS or within the 
next 25 hours TIS after the effective date of this AD, whichever 
occurs later, insert revisions to the Airplane Flight Manual (AFM) 
in accordance with paragraph B. 2. in the ACCOMPLISHMENT 
INSTRUCTIONS of Aviat SB No. 24, Dated: March 20, 1996, Revised 
November 22, 1996.
    (c) At the accumulation of 300 hours total TIS or within the 
next 25 hours TIS after the effective date of this AD, whichever 
occurs later, accomplish either (c)(1) or (c)(2) below:
    (1) Install an accelerometer and permanently mark the face with 
red marks (3/16-inch  x  1/16-inch) at the +6 g and -3 g hash marks, 
and install a placard (Aviat part number 2-7604-47) stating the 
gravity (``g'') force limitations within the pilot's clear view in 
accordance with paragraph B. 1. of the ACCOMPLISHMENT INSTRUCTIONS 
in Aviat SB No. 24, Date: March 20, 1996, Revised: November 22, 
1996; or
    (2) Fabricate and install a placard in the pilot's clear view 
using at least 1/8-inch letters that incorporates the following 
words:

``ACROBATIC MANEUVERS PROHIBITED.''

    (d) The installation of the placard and the insertion of the 
revisions into the AFM may be performed by the owner/operator 
holding at least a private pilot certificate as authorized by 
Sec. 43.7 of the Federal Aviation Regulations (14 CFR 43.7), and 
must be entered into the aircraft records showing compliance with 
this AD in accordance with Sec. 43.9 of the Federal Aviation 
Regulations (14 CFR 43.9).
    (e) Special flight permits may be issued in accordance with 
Secs. 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 action can be accomplished, provided no cracks 
are found during any inspections required by paragraph (a) of this 
AD. No special flight permits may be issued to any airplane with 
cracks in the upper longerons just aft of the rear cabane struts.
    (f) An alternative method of compliance or adjustment of the 
initial or repetitive compliance times that provides an equivalent 
level of safety may be approved by the Manager, Denver Aircraft 
Certification Office, 26805 East 68th Ave., Room 214, Denver, 
Colorado 80216. The request shall be forwarded through an 
appropriate FAA Maintenance Inspector, who may add comments and then 
send it to the Manager, Denver Aircraft Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Denver Aircraft Certification Office.

    (g) The inspection, modification, and replacements required by 
this AD shall be done in accordance with Aviat Aircraft Inc. Service 
Bulletin (SB) No. 24, Revised: November 22, 1996, and Aviat Aircraft 
Inc. Installation Instructions in Aviat Aircraft Inc. Kit No. S-2-
513, dated August 26, 1996, Revised: May 9, 1997. This incorporation 
by reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be 
obtained from Aviat Aircraft Inc., The Airport-Box No. 1240, 672 
South Washington Street, Afton, Wyoming, 83110. Copies may be 
inspected at the FAA, Central Region, Office of the Regional 
Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at 
the Office of the Federal Register, 800

[[Page 67711]]

North Capitol Street, NW., suite 700, Washington, DC.
    (h) This Amendment supersedes AD 96-09-08 R1, Amendment 39-9690.
    (i) This Amendment (39-10263) becomes effective on January 22, 
1998.

    Issued in Kansas City, Missouri, on December 16, 1997.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 97-33512 Filed 12-29-97; 8:45 am]
BILLING CODE 4910-13-U