[Federal Register Volume 59, Number 93 (Monday, May 16, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-10913]
[[Page Unknown]]
[Federal Register: May 16, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-ANE-53; Amendment 39-8909; AD 94-10-02]
Airworthiness Directives; Pratt & Whitney Canada Model PT6A-67D
Turboprop Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment supersedes an existing priority letter
airworthiness directive (AD), applicable to Pratt & Whitney Canada
(PWC) PT6A-67D turboprop engines, that currently requires inspections
of the compressor turbine (CT) disk and blades for cracking and other
irregularities using visual inspections and fluorescent penetrant
inspections (FPI). That AD also requires amending the Beech Model 1900D
Airplane Flight Manual (AFM) and installing a placard that alerts the
pilot of this requirement. This amendment continues all the
requirements of the current priority letter AD and requires the
installation of parts having an improved design including a CT stator
assembly, a CT shroud housing, CT turbine blades, feather seals, and a
small exit duct assembly. This amendment is prompted by the
manufacturer developing new design improvements that will reduce the
susceptibility of the CT blades to high cycle fatigue (HCF) damage. The
actions specified by this AD are intended to prevent engine failure and
inflight engine shutdown due to HCF failure of the CT blades.
DATES: Effective June 15, 1994.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of June 15, 1994.
ADDRESSES: The service information referenced in this AD may be
obtained from Pratt & Whitney Canada, 1000 Marie-Victorin, Longueil,
Quebec, Canada J4G 1A1. This information may be examined at the Federal
Aviation Administration (FAA), New England Region, Office of the
Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA
01803-5299; or at the Office of the Federal Register, 800 North Capitol
Street, NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Mark A. Rumizen, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (617)
238-7137, fax (617) 238-7199.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations by superseding priority letter airworthiness
directive (AD) 92-27-19, which is applicable to Pratt & Whitney Canada
(PWC) PT6A-67D turboprop engines, was published in the Federal Register
on November 26, 1993 (58 FR 62296). That action proposed to retain the
inspections and Airplane Flight Manual (AFM) revisions required by the
current AD, but would also require installation at the next shop visit
after the effective date of this AD, or December 31, 1994, whichever
occurs first, of the improved compressor turbine (CT) turbine stator
assembly, CT shroud housing, small exit duct assembly, CT blades, and
feather seals. Installation of this hardware constitutes terminating
action to the inspections required by this AD. PWC has advised the FAA
that December 31, 1994, is the earliest compliance end-date possible
due to parts availability. The actions are required to be accomplished
in accordance with PWC Service Bulletin (SB) No. 14128, Revision 3,
dated April 19, 1993; PWC SB No. 14132, Revision 1, dated May 12, 1993;
and PWC SB 14142, Revision 1, dated May 12, 1993. Transport Canada,
which is the airworthiness authority of Canada, classified these
service bulletins as mandatory and issued AD CF-92-25-R1, dated June 1,
1993, in order to assure the airworthiness of these PWC PT6A-67D
engines in Canada.
This engine model is manufactured in Canada and is type
certificated for operation in the United States under the provisions of
Section 21.29 of the Federal Aviation Regulations and the applicable
bilateral airworthiness agreement. Pursuant to this bilateral
airworthiness agreement, Transport Canada has kept the FAA informed of
the situation described above. The FAA has examined the findings of
Transport Canada, reviewed all available information, and determined
that AD action is necessary for products of this type design that are
certificated for operation in the United States.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comment received.
The commenter concurs with the rule as proposed.
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 as proposed.
There are approximately 100 engines of the affected design in the
worldwide fleet. The FAA estimates that 87 engines installed on
aircraft of U.S. registry will be affected by this AD, that it will
take approximately 40 work hours per engine to install the improved
hardware, and that the average labor rate is $55 per work hour. PWC
advises the FAA that it will reimburse operators for the cost of labor
and the cost of required parts. Based on these figures, the total cost
impact of the AD on U.S. operators is estimated to be negligible.
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 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 14 CFR part
39 of the Federal Aviation Regulations as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
94-10-02 Pratt & Whitney Canada: Amendment 39-8909 Docket 93-ANE-
53.
Applicability: Pratt & Whitney Canada (PWC) Model PT6A-67D
turboprop engines with serial numbers prior to PC-E114100, installed
on but not limited to Beech Model 1900D airplanes.
Compliance: Required as indicated, unless accomplished
previously.
To prevent engine failure and inflight engine shutdown due to
high cycle fatigue (HCF) failure of the compressor turbine (CT)
blades, accomplish the following:
(a) Prior to further flight, amend the Beech Model 1900D
Aircraft Flight Manual (AFM), Part Number (P/N) 129-590000-3, by
inserting the following requirements between pages 2-4 and 2-5:
ENGINE OPERATING LIMITATIONS
Gas Generator RPM (N1)--Continuous operation of the gas
generator between 94.0% and 97.1% is prohibited.
Notes
1. This limitation does not prohibit the use of N1's between
94.0% and 97.1% when the pilot in command determines that the power
setting is required for the safe operation of the airplane. If such
occurrences exceed 5 minutes, the engine(s) must be inspected in
accordance with Pratt & Whitney Canada Service Bulletin No. 14128,
Revision 3, dated April 19, 1993.
2. This limitation does not prohibit the use of static Take-Off
Power and Maximum Continuous Power between 94.0% and 97.1% N1 to
meet the required Take-Off performance. If such occurrences exceed 5
minutes, the engine(s) must be inspected in accordance with Pratt &
Whitney Canada Service Bulletin No. 14128, Revision 3, dated April
19, 1993.
3. Operation at 94.0% and below, and at 97.1% and above are
permitted. Continuous operation at 94.1% through 97.0% is
prohibited.
4. ``Continuous Operation'' means time periods exceeding 5
minutes.
5. High Speed Cruise Power Tables found in the Pilot's Operating
Manual may produce N1's in the prohibited range. Flights should be
planned using Intermediate or Long Range Power settings.
6. The goal of the operator should be to keep the total time of
operation in the prohibited range to the absolute minimum, since the
effects of operating between N1's of 94.0% and 97.1% are cumulative.
PLACARDS
Located in front of the pilot on the aft edge of the glareshield
between the Master Caution annunciator and the fire extinguisher
control switch:
CONTINUOUS OPERATION BETWEEN 94.0% AND 97.1% N1 IS PROHIBITED--SEE
AFM''
(b) Compliance with the requirements of paragraph (a) of this AD
may also be accomplished by inserting a copy of this AD into the
Beech Model 1900D AFM.
(c) Prior to further flight, install the placard as specified in
paragraph (a) of this AD.
(d) For engines that have not been inspected prior to the
effective date of this AD in accordance with PWC SB No. 14128,
Revision 1, dated November 13, 1992, or debladed and inspected in
accordance with PWC SB No. 14128, Revision 2, dated December 22,
1992, or PWC SB No. 14128, Revision 3, dated April 19, 1993,
accomplish the following:
(1) For engines with Serial Numbers PC-E114001 to PC-E114044,
within 25 hours time in service (TIS) after the effective date of
this AD, deblade the CT disk, inspect the entire disk surface area
and fir tree area of the CT blades for cracking and the trailing
edge of the blade airfoil section for irregularities, and replace,
if necessary, with serviceable parts, in accordance with the
Accomplishment Instructions of PWC SB No. 14128, Revision 3, dated
April 19, 1993.
(2) For engines with Serial Numbers PC-E114045 to PC-E114099,
within 50 hours TIS after the effective date of this AD, deblade the
CT disk, inspect the entire disk surface area and fir tree area of
the CT blades for cracking, and replace, if necessary, with
serviceable parts, in accordance with the Accomplishment
Instructions of PWC SB No. 14128, Revision 3, dated April 19, 1993.
(e) For engines that have been inspected in accordance with PWC
SB No. 14128, Revision 1, dated November 13, 1992, prior to the
effective date of this AD, deblade the CT disk, inspect the entire
disk surface area and fir tree area of the CT blades for cracking,
and replace, if necessary, with serviceable parts, in accordance
with the Accomplishment Instructions of PWC SB No. 14128, Revision
3, dated April 19, 1993, as follows:
(1) For blade sets with greater than 600 hours TIS since new on
the effective date of this AD, deblade, inspect, and replace, if
necessary, within the next 50 hours TIS.
(2) For blade sets with greater than or equal to 250 hours TIS,
and less than or equal to 600 hours TIS, since new, on the effective
date of this AD, deblade, inspect, and replace, if necessary, within
the next 100 hours TIS.
(3) For blade sets with less than 250 hours TIS since new on the
effective date of this AD, deblade, inspect, and replace, if
necessary, within the next 250 hours TIS.
(f) For uninstalled CT disk and blade assemblies that have not
been inspected in accordance with the Accomplishment Instructions of
PWC SB No. 14128, Revision 2, dated December 22, 1992, or PWC SB No.
14128, Revision 3, dated April 19, 1993, in the preceding 250 hours
TIS from the effective date of this AD, deblade the CT disk, inspect
the entire disk surface area and fir tree area of CT blades for
cracking, and replace, if necessary, with serviceable parts, in
accordance with the Accomplishment Instructions of PWC SB No. 14128,
Revision 3, dated April 19, 1993, prior to installation.
(g) For engines with CT disk and blade assemblies that have been
debladed and inspected in accordance with the Accomplishment
Instructions of PWC SB No. 14128, Revision 2, dated December 22,
1992, or PWC SB No. 14128, Revision 3, dated April 19, 1993, prior
to the effective date of this AD, within 250 hours TIS since the
last deblading and inspection, deblade the CT disk, inspect the
entire disk surface area and fir tree area of CT blades for
cracking, and replace, if necessary, with serviceable parts, in
accordance with the Accomplishment Instructions of PWC SB No. 14128,
Revision 3, dated April 19, 1993.
(h) For CT disk and blade assemblies that have been debladed and
inspected in accordance with paragraphs (d), (e), (f), and (g) of
this AD, deblade the CT disk, reinspect the entire disk surface area
and fir tree area of CT blades for cracking, and replace, if
necessary, with serviceable parts, in accordance with the
Accomplishment Instructions of PWC SB No. 14128, Revision 3, dated
April 19, 1993, at intervals not to exceed 250 hours TIS since the
last deblading and inspection performed in accordance with the
Accomplishment Instructions of PWC SB No. 14128, Revision 3, dated
April 19, 1993.
(i) Install a CT stator assembly, a CT shroud housing, and a
small exit duct assembly in accordance with PWC SB No. 14132,
Revision 1, dated May 12, 1993, at the next shop visit after the
effective date of this AD, or December 31, 1994, whichever occurs
first.
(j) Install CT blades and feather seals in accordance with PWC
SB No. 14142, Revision 1, dated May 12, 1993, at the next shop visit
after the effective date of this AD, or December 31, 1994, whichever
occurs first.
(k) For the purpose of this AD, a shop visit is defined as when
major engine flanges are separated.
(l) Installation of improved hardware in accordance with
paragraphs (i) and (j) of this AD constitutes terminating action for
the inspections required by paragraphs (d) through (h) of this AD.
(m) 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, Engine Certification Office. The
request should be forwarded through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Engine Certification Office.
Note: Information concerning the existence of approved
alternative method of compliance with this AD, if any, may be
obtained from the Engine Certification Office.
(n) Special flight permits may be issued in accordance with 14
CFR 21.197 and 21.199 to operate the aircraft to a location where
the requirements of this AD can be accomplished.
(o) The inspections and modifications shall be done in
accordance with the following service bulletins:
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Document No. Pages Revision Date
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PWC SB No. 14128; Total pages: 5.......................... 1-5 3 April 19, 1993.
PWC SB No. 14132; Total pages: 6.......................... 1-6 1 May 12, 1993.
PWC SB No. 14142; Total pages: 7.......................... 1-7 1 May 12, 1993.
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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 Pratt & Whitney Canada, 1000
Marie-Victorin, Longueil, Quebec, Canada J4G 1A1. Copies may be
inspected at the FAA, New England Region, Office of the Assistant
Chief 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.
(p) This amendment supersedes priority letter AD 92-27-19,
issued December 28, 1992.
(q) This amendment becomes effective on June 15, 1994.
Issued in Burlington, Massachusetts, on April 29, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 94-10913 Filed 5-13-94; 8:45 am]
BILLING CODE 4910-13-P
