RIORITY LETTER AIRWORTHINESS DIRECTIVE

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PRIORITY LETTER AIRWORTHINESS DIRECTIVE

REGULATORY SUPPORT DIVISION
P.O. BOX 26460
OKLAHOMA CITY, OKLAHOMA 73125-0460

U.S. Department
of Transportation
Federal Aviation
Administration

DATE: April 22, 1999
��������������� 99-09-17

The Federal Aviation Administration (FAA) has received reports of crankshaft failures on Teledyne Continental Motors (TCM) O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, IO-550, TSIO-550, and TSIOL-550 series reciprocating engines. Since December 1998, the FAA obtained information regarding 7 crankshaft failures. The investigation revealed that the crankshafts failed due to cracks through the No. 2 or No. 5 cheeks. Analysis indicated that the crankshaft failures occurred early in the life of a new crankshaft, from 80 to 175 hours time-in-service (TIS). In addition, one crankshaft was found which had not failed but which had a crack initiation. TCM has advised the FAA that all of the fractures were due to a discrepancy in the counterweight bushing installation process, involving a tool which can damage the nitride surface of the cheek sufficient to create a crack which will propagate through the nitride layer. Such a crack will always result in failure of the crankshaft. All of the fractures have been grouped around certain manufacturing dates between January 1998 and December 1998, inclusive. Review of the manufacturing processes, basic metallurgy, nitride characteristics, dimensional characteristics, and supplier practices have not identified any other contributing causes. This condition, if not corrected, could result in crankshaft failure due to No. 2 and No. 5 cheek cracks, which could result in total engine power loss, in-flight engine failure, and possible forced landing.

The FAA has reviewed and approved the technical contents of TCM Critical Service Bulletin (CSB) 99-3, dated April 19, 1999, that lists serial numbers (S/Ns) of affected engines that were manufactured between January 1998 and December 1998, inclusive. This CSB also describes procedures for visual and ultrasonic (UT) inspections of specific areas of the No. 2 and No. 5 crankshaft cheeks. All inspections must be performed by TCM representatives, since it is a new procedure that only TCM-trained personnel are currently authorized to perform.

Since an unsafe condition has been identified that is likely to exist or develop on other engines of this same type design, this priority letter airworthiness directive (AD) requires a one-time visual and UT inspection of the No. 2 and No.�5 crankshaft cheeks for cracks. All crankshaft cheeks found cracked must be replaced with a serviceable crankshaft prior to further flight. There are approximately 80,000 TCM O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, IO-550, TSIO-550 and TSIOL-550 series reciprocating engines in the worldwide fleet, with approximately 68,000 in the U.S. fleet. 3,200 crankshafts were manufactured during the affected time period. Engines that were not manufactured, rebuilt, or overhauled, or that did not have a crankshaft installed in the field during that time period are not affected by this priority letter AD, which can be verified through log books or other maintenance records. Engines that may have an affected crankshaft installed must be checked for engine S/Ns listed in TCM CSB 99-3, dated April 19, 1999, and must be inspected for the S/Ns of field-installed new crankshafts manufactured between January 1, 1998, and December 31, 1998, inclusive. The actions are required to be accomplished in accordance with the CSB described previously.

This rule is issued under 49 U.S.C. Section 44701 (formerly section 601 of the Federal Aviation Act of 1958) pursuant to the authority delegated to me by the Administrator, and is effective immediately upon receipt of this priority letter.

99-09-17 TELEDYNE CONTINENTAL MOTORS: Priority Letter issued on April 22, 1999. Docket No. 99-NE-28-AD.

Applicability: Teledyne Continental Motors (TCM) O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, IO-550, TSIO-550 and TSIOL-550 series new and rebuilt reciprocating engines, manufactured between January 1, 1998, and December 31, 1998, inclusive, listed by serial number (S/N) in TCM Critical Service Bulletin (CSB) 99-3, dated April 19, 1999, and any other engine from the above series that has had a new crankshaft installed that was manufactured between January 1, 1998, and December 31, 1998, inclusive.

Note 1: Engine S/Ns can be found in log books or other maintenance records. For those engines that were overhauled in the field with factory new crankshafts, crankshaft S/Ns should be shown in work orders, log books, or other maintenance records.

Note 2: �This Priority Letter 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 request approval for an alternative method of compliance in accordance with paragraph (e) 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 prevent crankshaft failure due to No. 2 and No. 5 cheek cracks, which could result in total engine power loss, in-flight engine failure, and possible forced landing, accomplish the following:

(a) For those engines listed by S/N on pages 3 through 12 of TCM CSB 99-3 dated April 19, 1999, with 300 hours or less time-in-service (TIS) upon receipt of this priority letter AD, perform the crankshaft visual and ultrasonic (UT) inspections within 10 hours TIS after receipt of this priority letter AD, in accordance with sections A and B of
TCM CSB 99-3, dated April 19, 1999. These inspections must be performed by TCM representatives.

(1) If a crack is found, replace the crankshaft with a serviceable crankshaft of the same part number (P/N) prior to further flight.

(2) If no crack is found, reassemble the engine and return it to service.

(b) For those engines listed by S/N on pages 3 through 12 of TCM CSB 99-3, dated April 19, 1999, with more than 300 hours TIS upon receipt of this priority letter AD, perform the crankshaft visual and UT inspections at the next maintenance event, or within 50 hours TIS after receipt of this priority letter AD, whichever occurs first, in accordance with sections A and B of TCM CSB 99-3, dated April 19, 1999. These inspections must be performed by TCM representatives.

(1) If a crack is found, replace the crankshaft with a serviceable crankshaft of the same P/N prior to further flight.

(2) If no crack is found, reassemble the engine and return it to service.

(c) For any other engine with a crankshaft installed that was manufactured between January 1, 1998, and December�31, 1998, with 300 hours or less TIS upon receipt of this priority letter AD, perform the crankshaft visual and UT inspections within 10 hours TIS after receipt of this priority letter AD, in accordance with sections A and B of
TCM CSB 99-3, dated April 19, 1999. These inspections must be performed by TCM representatives.

(1) If a crack is found, replace the crankshaft with a serviceable crankshaft of the same P/N prior to further flight.

(2) If no crack is found, reassemble the engine and return it to service.

(d) For any other engine with a crankshaft installed that was manufactured between January 1, 1998, and December�31, 1998, with more than 300 hours TIS upon receipt of this priority letter AD, perform the crankshaft visual and UT inspections at the next maintenance event, or within 50 hours TIS after receipt of this priority letter AD, whichever occurs first, in accordance with sections A and B of TCM CSB 99-3, dated April 19, 1999. These inspections must be performed by TCM representatives.

(1) If a crack is found, replace the crankshaft with a serviceable crankshaft of the same P/N prior to further flight.

(2) If no crack is found, reassemble the engine and return it to service.

Note 3: Engines and crankshafts that are the subject of this priority letter AD were manufactured between January�1, 1998, and December 31, 1998, inclusive. Purchase and delivery dates of engines/crankshafts produced in December 1998 could have been in the January/February 1999 time frame and are therefore affected by this AD. Likewise, engines/crankshafts purchased/delivered in January/February 1998 could have been December 1997 production and are not affected by this AD. Use the S/N of the engine or crankshaft to determine applicability: engine S/Ns are listed in TCM CSB 99-3, dated April 19, 1999, while the crankshafts, not listed by S/N, were manufactured during 1998. See Note 4 for information on identifying crankshafts.

Note 4: The following information is provided to avoid confusion in crankshaft S/N interpretation. A typical crankshaft S/N could be C229805N. The first letter is the month of manufacture beginning with A � January and ending with L � December; therefore, C is March. The next two digits are the day of the month; in this example, the 22 nd. The next two digits are the year; in this example 1998. The final two digits are the sequential number of the crankshaft for a given day; in the example, this was the 5 th crankshaft produced that day. The final letter, "N", identifies this as a crankshaft S/N. Therefore, for this example: we have the 5 th crankshaft produced on March 22, 1998. For all practical purposes, you only need look for the year, i.e. 98 (fourth and fifth positions in the S/N sequence) because that will determine AD effectivity. The crankshaft S/N is stamped on the edge of the propeller flange.

Note 5: The engine S/Ns listed in TCM CSB 99-3 contain only the numerical portion of the S/N. Rebuilt engines will have the letter "R" at the end of the six digit numerical portion while new engines use only the six digit numerical sequence.

(e) 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, Atlanta Aircraft Certification Office. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Atlanta Aircraft Certification Office.

Note 6: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Atlanta Aircraft Certification Office.

(f) 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.

(g) Copies of the applicable service information may be obtained from Teledyne Continental Motors, PO Box 90, Mobile, AL 36601; telephone toll free (888) 200-7565. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

(h) Priority Letter AD 99-09-17, issued April 22, 1999, becomes effective upon receipt.

FOR FURTHER INFORMATION CONTACT:

Jerry Robinette, Aerospace Engineer, Atlanta Aircraft Certification Office, FAA, Small Airplane Directorate, One Crown Center, 1895 Phoenix Blvd., Suite 450, Atlanta, GA 30349; telephone (770) 703-6096, fax (770) 703-6097.