[Federal Register Volume 60, Number 123 (Tuesday, June 27, 1995)]
[Rules and Regulations]
[Pages 33101-33104]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-15558]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-ANE-33; Amendment 39-9288; AD 95-13-08]


Airworthiness Directives; Pratt & Whitney Canada Model PT6A-67D 
Turboprop Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing 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 a requirement to 
restrict continuous engine operation above 94.0% and below 97.1% N1 
(Gas Generator RPM). In addition, that AD 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 continues the requirements of the current AD 
and adds the requirements to remove the placard from the cockpit and to 
remove the amendment to the AFM after installation of the improved 
engine components. This amendment is prompted by reports from operators 
and the manufacturer stating that the engine RPM operating restriction 
is not required after installation of the improved engine components, 
and that this engine operating restriction can impact aircraft 
handling. The actions specified by this AD are intended to prevent 
aircraft handling problems due to imposition of the engine RPM 
restriction.

DATES: Effective July 12, 1995.
    The incorporation by reference of certain publications listed in 
the regulations was approved by the Director of the Federal Register as 
of June 15, 1994.
    Comments for inclusion in the Rules Docket must be received on or 
before August 28, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 95-ANE-33, 12 New England 
Executive Park, Burlington, MA 01803-5299.
    The service information referenced in this AD may be obtained from 
. This information may be examined at the FAA, New England Region, 
Office of the Assistant Chief Counsel, Burlington, MA; 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: On May 16, 1994, the Federal Aviation 
Administration (FAA) issued airworthiness directive (AD) 94-10-02, 
Amendment 39-8909 (59 FR 25295, May 16, 1994), applicable to Pratt & 
Whitney Canada (PWC) PT6A-67D turboprop engines, to require deblading 
the compressor turbine (CT) disk; and inspecting the entire disk 
surface area and fir tree areas of the CT blades for cracking and the 
trailing edge of the blade airfoil section for irregularities, using 
visual inspections and fluorescent penetrant inspections (FPI). These 
inspections are required until installation of parts having an improved 
design turbine blades, feather seals, and a small exit duct assembly. 
That AD also requires amending the Beech Model 1900D Airplane Flight 
Manual (AFM) by inserting requirements that describe restricting 
continuous engine operation above 94.0% and below 97.1% N1 (Gas 
Generator RPM); and installing a placard that alerts the pilot of this 
restriction. That action was prompted by reports of CT blade failures 
due to high cycle fatigue (HCF) fractures in the fir tree area of the 
blade while exposed to normal engine vibrations and by the manufacturer 
developing new design improvements that will reduce the susceptibility 
of the CT blades to HCF damage. That condition, if not corrected, could 
result in aircraft handling problems due to imposition of the engine 
RPM restriction.
    Since the issuance of that AD, operators of Beech 1900D aircraft 
and the manufacturer have stated that the engine RPM operating 
restriction is not required after installation of the improved engine 
components, and that the engine operating restriction can impact 
aircraft handling. The placard and AFM amendment currently restrict 
continuous engine operation above 94.0% and below 97.1% N1, where 
continuous operation is defined as time [[Page 33102]] periods 
exceeding 5 minutes. In some situations, this restriction could require 
the pilot to adjust the engine power level during critical flight 
segments, such as takeoff, thus increasing pilot workload. Therefore, 
this superseding AD repeats the compliance requirements of the current 
AD, and adds the requirement to remove the placard from the cockpit and 
remove the amendment to the AFM after installation of the improved 
engine components.
    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.
    PWC has issued Service Bulletin (SB) No. 14128, Revision 3, dated 
April 19, 1993, that specifies procedures for CT blade inspections; SB 
No. 14132, Revision 1, dated May 12, 1993, that specifies procedures 
for CT stator vane replacement; and SB 14142, Revision 1, dated May 12, 
1993, that specifies procedures for CT blade replacement. Transport 
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.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other engines of this same type design, this AD 
supersedes AD 94-10-02 to continue the requirements of the current AD 
and add the requirements to remove the placard from the cockpit and to 
remove the amendment to the AFM after installation of the improved 
engine components. The actions are required to be accomplished in 
accordance with the SB's described previously.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications should identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 95-ANE-33.'' The postcard will be date stamped and 
returned to the commenter.
    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and is not a ``significant regulatory action'' 
under Executive Order 12866. It has been determined further that this 
action involves an emergency regulation under DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979). If it is determined 
that this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, 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. 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 removing Amendment 39-8909, (59 FR 
25295, May 16, 1994), and by adding a new airworthiness directive, 
Amendment 39-9288, to read as follows:

95-13-08  Pratt & Whitney Canada: Amendment 39-9288. Docket 95-ANE-
33. Supersedes AD 94-10-02, Amendment 39-8909.

    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.

    Note: This airworthiness directive (AD) applies to each engine 
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 engines that have been 
modified, altered, or repaired so that the performance of the 
requirements of this AD is affected, the owner/operator must use the 
authority provided in paragraph (o) to request approval from the 
Federal Aviation Administration (FAA). This approval may address 
either no action, if the current configuration eliminates the unsafe 
condition, or different actions necessary to address the unsafe 
condition described in this AD. Such a request should include an 
assessment of the effect of the changed configuration on the unsafe 
condition addressed by this AD. In no case does the presence of any 
modification, alteration, or repair remove any engine from the 
applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent aircraft handling problems due to imposition of the 
engine RPM restriction, accomplish the following: [[Page 33103]] 
    (a) For those operators that have previously complied with AD 
94-10-02, this AD requires compliance with only paragraph (n).
    (b) 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''

    (c) Compliance with the requirements of paragraph (b) of this AD 
may also be accomplished by inserting a copy of this AD into the 
Beech Model 1900D AFM.
    (d) Prior to further flight, install the placard as specified in 
paragraph (b) of this AD.
    (e) 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 AD 
94-10-02, June 15, 1994, 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 AD 94-10-02, June 
15, 1994, 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.
    (f) 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 AD 94-10-02, June 15, 1994, deblade, inspect, 
and replace, if necessary, within the next 50 hours TIS after the 
effective date of AD 94-10-02, June 15, 1994.
    (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 AD 94-10-02, June 15, 1994, deblade, inspect, and replace, 
if necessary, within the next 100 hours TIS after the effective date 
of AD 94-10-02, June 15, 1994.
    (3) For blade sets with less than 250 hours TIS since new on the 
effective date of AD 94-10-02, June 15, 1994, deblade, inspect, and 
replace, if necessary, within the next 250 hours TIS after the 
effective date of AD 94-10-02, June 15, 1994.
    (g) 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 AD 94-10-02, June 15, 1994, 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.
    (h) 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 AD 94-10-02, June 15, 1994, 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.
    (i) For CT disk and blade assemblies that have been debladed and 
inspected in accordance with paragraphs (e), (f), (g), and (h) 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.
    (j) 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 within 30 days after the effective 
date of this AD, whichever occurs first.
    (k) 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 30 days after the effective 
date of this AD, whichever occurs first.
    (l) For the purpose of this AD, a shop visit is defined as when 
major engine flanges are separated.
    (m) Installation of improved hardware in accordance with 
paragraphs (j) and (k) of this AD constitutes terminating action for 
the inspections required by paragraphs (e) through (i) of this AD.
    (n) For aircraft equipped with engines that have complied with 
paragraphs (j) and (k) of this AD, or AD 94-10-02, accomplish the 
following:
    (1) Remove the amendment to the Beech Model 1900D AFM, P/N 129-
590000-3, described in paragraphs (b) or (c) of this AD.
    (2) Remove the placard described in paragraph (d) of this AD.
    (o) 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.

    (p) Special flight permits may be issued in accordance with 
sections 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 requirements of this AD can be accomplished.
    (q) The inspections and modifications shall be done in 
accordance with the following SB's:

[[Page 33104]]
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       Document No.         Pages    Revision             Date          
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PWC SB No. 14128.........      1-5          3  April 19, 1993.          
  Total pages: 5.........                                               
PWC SB No. 14132.........      1-6          1  May 12, 1993.            
  Total pages: 6.........                                               
PWC SB No. 14142.........      1-7          1  May 12, 1993.            
  Total pages: 7.........                                               
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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.
    (r) This amendment becomes effective on July 12, 1995.

    Issued in Burlington, Massachusetts, on June 15, 1995.
James C. Jones,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 95-15558 Filed 6-23-95; 10:11 am]
BILLING CODE 4910-13-U