[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]


-----------------------------------------------------------------------


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.

-----------------------------------------------------------------------

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: 

----------------------------------------------------------------------------------------------------------------
                       Document No.                             Pages          Revision             Date        
----------------------------------------------------------------------------------------------------------------
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.       
----------------------------------------------------------------------------------------------------------------

    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