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 Federal Register Information
 Header Information
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 89-ANE-44-AD; Amendment 39-12505; AD 2001-23-08]
RIN 2120-AA64
Airworthiness Directives; Hartzell Propeller Inc. ( )HC-( )2Y( )-( ) Propellers
PDF Copy (If Available):
Preamble Information
AGENCY: Federal Aviation Administration, DOT
ACTION: Final rule
SUMMARY: This amendment supersedes priority letter AD 90-02-23, that is applicable to certain Hartzell Propeller Inc. ( )HC-( )2Y( )-( ) propellers. That priority letter currently requires repetitive visual inspections of propeller hubs for cracks using a 10X glass and, if necessary, removal of cracked hubs and replacement with serviceable parts. This amendment changes the frequency and method of inspection by requiring initial and repetitive eddy current inspections (ECI) of the propeller hub fillet radius for cracks and requires that certain model propeller hubs be removed from service. In addition, this AD allows installation of an improved design propeller hub as terminating action to the repetitive ECI. This amendment is prompted by reports of cracked propeller hubs found in service after they had been inspected in accordance with the visual inspections required by the current AD. The actions specified in this AD are intended to prevent failure of the propeller hub resulting from cracks, that can cause blade separation and subsequent loss of aircraft control.
DATES: Effective date December 24, 2001. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of December 24, 2001.
ADDRESSES: The service information referenced in this AD may be obtained from Hartzell Propeller Inc., Product Support Department, One Propeller Place, Piqua, OH 45356; telephone: (937) 778-4379, fax: (937) 778-4391. This information may be examined, by appointment, at the Federal Aviation Administration (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:
Tomaso DiPaolo, Aerospace Engineer, Chicago Aircraft Certification Office, FAA, Small Airplane Directorate,
2300 East Devon Avenue, Des Plaines, IL 60018; telephone: (847) 294-7031, fax: (847) 294-7834.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding priority letter airworthiness directive (AD) 90-02-23, applicable to certain Hartzell Propeller Inc. ( )HC-( )2Y( )-( ) propellers, was published in the Federal Register on January 27, 1999 (64 FR 4061). That action proposed to change the frequency and method of inspection by requiring initial and repetitive ECI of the propeller hub fillet radius for cracks and, if necessary, removal and replacement of cracked hubs with serviceable parts. In addition, that action proposed to expand the models of propellers affected and allow installation of an improved design propeller hub as terminating action to the repetitive ECI.
Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
Replace "A" Hub Design With "B" Hub Design
The manufacturer notes that since the NPRM was published, there have been some instances of fractures involving the rear hub half of the "A" suffix serial numbered hubs. Since the rear half of the hub cannot be readily inspected, the manufacturer recommends the replacement of "A" suffix hubs with the current "B" suffix hubs, which incorporate a new design.
The FAA agrees in part and has incorporated into this AD the replacement requirements for "A" suffix hubs per Hartzell Service Bulletin HC-SB-61-227, Revision 2, dated May 8, 2000. The FAA is also considering expanding the applicability of this action in the future to remove from service all "A" suffix hub designs, regardless of the aircraft model they are installed on.
Current AD is Adequate
One commenter contends that the current AD, requiring visual inspections using a 10 x glass at intervals of 50 hours, adequately detects cracked hubs prior to catastrophic failure. Since a new design hub is available, and no catastrophic failures have been attributed to a failure to detect a crack using the current inspections, the commenter contends that there is no need for a more expensive eddy current inspection.
The FAA does not agree. The service history of these propellers since the current AD was issued indicates that the visual inspections are not working as intended. Two hubs that were apparently inspected visually did, in fact, fail in service, releasing propeller blades. In another instance, a crack was discovered during overhaul, 32 hours following a visual inspection performed in accordance with the current AD. Other instances were reported where cracks were found only after unusual vibrations or grease and oil on the windshield prompted examinations of the propeller hubs, which had passed the visual inspection required by the current AD. As a result, the FAA believes that an ECI of the propeller hub is required in order to increase the probability of detection and decrease the risk of in-service failure of the hub.
Increase Repetitive Inspection Period
One commenter requests that the repetitive inspection period be changed from 150 hours to 400-500 hours, then shortened after more data is collected. The commenter feels that the cost analysis does not reflect the true costs of having to perform ECI every 150 hours, particularly for operators located in remote areas of the country.
The FAA does not agree. The service history demonstrates the need for ECI in lieu of the visual inspection. The 150-hour interval is based on an engineering evaluation of crack growth. The cost analysis estimates the average cost to perform the mandated actions. Those costs could be higher in certain cases. Operators could mitigate higher costs by seeking training and certification to perform the ECI at the operator's location. Operators desiring to pursue this alternative should contact Hartzell. In addition, the AD allows for replacement of certain propeller hubs as terminating action for the repetitive ECI.
Mandatory Overhaul
One commenter notes that instead of requiring repetitive ECI and making design changes to the propeller, operators should be required to adhere to the manufacturer's recommended overhaul interval of 5 years or 1,000 hours. The commenter is concerned that the design changes will introduce a new set of problems, and in the commenter's opinion, while a propeller failure is extremely critical, the older Hartzell propeller designs are extremely reliable when properly maintained.
The FAA does not agree. The cracks were not caused by the lack of maintenance. The repetitive ECI inspection is required at intervals of 150 hours which is far more often than a 5-year or 1,000-hour time between overhaul.
Seriousness of Propeller Failure
One commenter expresses concerns that the FAA has treated the potential failure of these propeller hubs with too much complacency, allowing visual inspections using a 10X glass. The commenter notes that a crack detected using a 10X glass may well be very close to failure and that any propeller hub failure exposes the aircraft to serious control problems and could likely result in a loss of the aircraft.
The FAA agrees that cracks in a propeller hub present a very serious unsafe condition. When the current AD was issued, the FAA viewed a visual inspection with a very short repetitive interval as sufficient to address that serious unsafe condition. Based on the service history since then, the FAA has determined that an inspection method with a higher sensitivity of crack detection is needed, and this AD will require an ECI with longer intervals.
AD Applicability and Aircraft Names
One commenter suggests changes to the aircraft names listed in the AD. The commenter notes that two different type certificates cover aircraft named Britten Norman BN-2, and the AD does not clearly indicate which aircraft may have the affected propellers. The commenter also notes that the phrase "agricultural category" does not clearly identify which aircraft may have an affected propeller. The commenter also notes that the Hartzell Y-shank propeller does not appear to be eligible for installation on a number of the aircraft listed in the AD.
The FAA agrees that the applicability of the proposed AD was not clear and that changes are needed to provide operators with an unambiguous identification of the affected propellers. The FAA has reviewed the aircraft type certificate data sheets and supplemental type certificate data sheets and has changed the reference to the "Britten Norman BN-2( ) aircraft" to "Pilatus Britten Norman or Britten Norman BN-2 series aircraft (also known as the Islander or Trislander)." The AD applies to all Hartzell Y-shank propellers installed on any Britten Norman or Pilatus Britten Norman BN-2 series aircraft that have a Textron Lycoming 540 series engine. The AD does not apply to the Textron Lycoming 541 series engine. The general statement of applicability also includes all Hartzell Y-shank propeller installed on any aircraft certificated in the acrobatic category or that has ever been used for agricultural purposes. The list of aircraft types that follows that general statement includes the changes the commenter noted, "Great Lakes Aircraft Co. 2T-1 series aircraft" has been changed to "Great Lakes Aircraft Co. or Chaparral Motors 2T-1 series aircraft," Piper "PA-36-600" has been changed to "Piper PA-36-300." The list includes those aircraft types that may have a Hartzell Y-shank propeller installed through supplemental type certificate (STC). That STC approval may not be reflected on the aircraft's type certificate data sheet.
Other Changes
Since the FAA published this proposal, the manufacturer has updated Service Bulletin HC-SB-61-227. This AD references Hartzell Propeller Service Bulletin HC-SB-61-227, Revision 2, dated May 8, 2000.
The FAA has also made editorial changes in the requirements of the AD. Those changes do not alter the substance of the requirements from what was proposed.
After careful review of the available data, including the comments 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 any operator nor increase the scope of the AD.
Economic Analysis
There are approximately 10,800 propellers of the affected design in the worldwide fleet. The FAA estimates that 4,600 propellers installed on aircraft of U.S. registry would be affected by ECI action of this AD, that it would take approximately 1 work hour per propeller to accomplish the ECI actions, and that the average ECI rate is $150 per work hour. Based on these figures, the total cost impact of the proposed AD on U.S. operators per ECI is estimated to be $690,000. The FAA estimates that 2,100 propellers installed on aircraft of U.S. registry would be affected by the replacement action, and that it would take approximately 6 work hours to replace a propeller, the average parts cost for a replacement propeller hub is $2,600, and that the average rate is $60 per work hour. Based on these figures, the total cost impact of the proposed AD on U.S. operators for replacement is estimated to be $6,216,000.
Regulatory Impact
This final rule does not have federalism implications, as defined in Executive Order 13132, because it would 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this final rule.
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 the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 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 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD), Amendment 39-12505, to read as follows:
Regulatory Information
Footer Information
Issued in Burlington, Massachusetts, on November 7, 2001.
Donald E. Plouffe,
Acting Manager, Engine and Propeller Directorate,
Aircraft Certification Service.
[FR Doc. 01-28689 Filed 11-16-01; 8:45 am]
BILLING CODE 4910-13-P
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