Airworthiness Directives; Dowty Aerospace Propellers Model R381/6-123-F/5 Propellers

[Federal Register Volume 66, Number 51 (Thursday, March 15, 2001)]
[Rules and Regulations]
[Pages 15022-15024]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-5735]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-43-AD; Amendment 39-12143; AD 99-18-18 R1]
RIN 2120-AA64


Airworthiness Directives; Dowty Aerospace Propellers Model R381/
6-123-F/5 Propellers

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment revises an existing airworthiness directive 
(AD) that is applicable to Dowty Aerospace Propellers Model R381/6-123-
F/5 propellers, that requires initial and repetitive visual and 
ultrasonic inspections of propeller blades for cracks across the camber 
face, and, if blades are found cracked, replacement with serviceable 
blades. This amendment is prompted by an engineering analysis of field 
service data and certification testing that indicate that the 
repetitive visual inspection interval can be safely increased and that 
the ultrasonic inspections can be eliminated. The actions specified in 
this proposed AD are intended to detect propeller blade cracks and 
propagation, which if not detected could result in propeller blade 
separation and possible aircraft loss of control.

DATES: Effective April 19, 2001. The incorporation by reference of 
certain publications listed in the regulations is approved by the 
Director of the Federal Register as of April 19, 2001.

ADDRESSES: The service information referenced in this AD may be 
obtained from Dowty Aerospace Propellers, Anson Business Park, 
Cheltenham Road East, Gloucester GL29QN, England; telephone: 44 1452 
716000, fax: 44 1452 716001. This information may be examined at the 
FAA, New England Region, Office of the Regional Counsel, 12 New England 
Executive Park, Burlington, MA, or at the Office of the Federal 
Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Kirk Gustafson, Aerospace Engineer, 
Boston Aircraft Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; 
telephone: 781-238-7190, fax: 781-238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by revising AD 99-18-18, 
Amendment

[[Page 15023]]

39-11284 (64 FR 47661, September 1, 1999), which is applicable to Dowty 
Aerospace Propellers Model R381/6-123-F/5 propellers, was published in 
the Federal Register on August 21, 2000 (65 FR 50667). The action 
proposed to increase the propeller blade crack inspection intervals. 
For repetitive visual inspection intervals, the proposed increase was 
from 50 to 300 hours time-in-service (TIS) since last inspection, and 
for repetitive ultrasonic inspection intervals the proposed increase 
was from 200 to 600 hours TIS.

Comment Received

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

Eliminate Ultrasonic Inspection and Increase Inspection Interval

    A comment from the manufacturer recommends elimination of 
ultrasonic inspections, based on analysis that concluded that initial 
and repetitive visual inspection intervals are adequate. The 
manufacturer states that the engineering analysis of field service data 
did not reveal a specific root cause for the original cracked blade. It 
is suspected that an unusual circumstance may have been involved, such 
as an unreported impact with a ground vehicle. However, to ensure the 
structural integrity of blades in service, initial and repetitive 
visual inspections must be done, and, as a result of the analysis, 
these inspections are being allowed at increased intervals as specified 
in a new revision to the applicable service bulletin.
    The FAA agrees. The engineering data provided to the FAA by the 
manufacturer indicates there are no specific structural concerns, 
manufacturing quality issues, or fatigue mechanisms that would justify 
the need for initial and repetitive ultrasonic inspections, and that an 
increased repetitive visual inspection interval is appropriate. The 
inspections were originally proposed by the manufacturer and mandated 
by the FAA to address an unknown cause for a cracked blade found in 
service. These inspections were based on a need for a conservative 
control program as an interim action, while a detailed investigation 
was performed. As a measure of conservatism, the extended repetitive 
inspection interval is being retained. The inspection coincides with 
existing propeller maintenance tasks so as not to create an undue 
burden while providing additional margin against potential but 
unanticipated causes for propeller blade cracks. This amendment has 
been revised to eliminate the ultrasonic inspections, increase the 
visual inspection intervals, and reference the newly revised service 
bulletin.
    After careful review of the available data, including the comment 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on an operator nor increase the scope of 
the AD.

Economic Analysis

    The FAA estimates that there are six propellers of the affected 
design installed on aircraft of U.S. registry. The FAA also estimates 
that it would take approximately four work hours per propeller to 
accomplish a visual inspection, and that the average labor rate is $60 
per work hour. A propeller will average three visual inspections per 
year. Based on these figures for the six propellers, the yearly cost 
impact for this AD is estimated to be $4,320.

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, 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 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-11284 (64 FR 
47661, September 1, 1999), and by adding a new airworthiness directive 
(AD), and by adding a new airworthiness directive (AD), Amendment 39-
12143 to read as follows:

99-18-18  R1, Dowty Aerospace Propellers: Docket 99-NE-43-AD. 
Revises AD 99-18-18, Amendment 39-11284.

    Applicability: Dowty Aerospace Propellers Model R381/6-123-F/5 
propellers, installed on but not limited to SAAB 2000 series 
airplanes.

    Note 1: This airworthiness directive (AD) applies to each 
propeller 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 propellers 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 (c) 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, unless accomplished 
previously.
    To detect propeller blade cracks and propagation, which if not 
detected could result in propeller blade separation and possible 
aircraft loss of control, accomplish the following:

Visual Inspections

    (a) Perform initial and repetitive visual inspections of 
propeller blades for cracks across the camber face in accordance 
with the Accomplishment Instructions of Dowty Aerospace Propellers 
Service Bulletin (SB) No. S2000-61-75, Revision 4, dated September 
28, 2000, as follows:
    (1) Initially, conduct a visual inspection within 50 hours time-
in-service (TIS) after the effective date of this AD.
    (2) Thereafter, inspect at intervals not to exceed 600 hours TIS 
since last inspection.
    (3) Replace cracked propeller blades prior to further flight 
with serviceable blades.
    (b) [Reserved]

Alternative Method of Compliance

    (c) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be

[[Page 15024]]

used if approved by the Manager, Boston Aircraft Certification 
Office (ACO). Operators shall submit their requests through an 
appropriate FAA Principal Maintenance Inspector, who may add 
comments and then send it to the Manager, Boston ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Boston ACO.

Special Flight Permits

    (d) 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 aircraft to a location where the 
inspection requirements of this AD can be accomplished.

Incorporation by Reference

    (e) The actions required by this AD must be done in accordance 
with the Accomplishment Instructions of Dowty Aerospace Propellers 
Service Bulletin (SB) No. S2000-61-75, Revision 4, dated September 
28, 2000. 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 Dowty Aerospace 
Propellers, Anson Business Park, Cheltenham Road East, Gloucester 
GL29QN, England; telephone: 44 1452 716000, fax: 44 1452 716001. 
Copies may be inspected at the FAA, New England Region, Office of 
the Regional Counsel, 12 New England Executive Park, Burlington, MA, 
or at the Office of the Federal Register, 800 North Capitol Street, 
NW, suite 700, Washington, DC.

Effective Date

    (f) This amendment becomes effective on April 19, 2001.

    Issued in Burlington, Massachusetts, on March 1, 2001.
David A. Downey,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service
[FR Doc. 01-5735 Filed 3-14-01; 8:45 am]
BILLING CODE 4910-13-P

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