DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION
14 CFR Part 39
[Docket No. FAA-2007-0051; Directorate Identifier 2007-NE-37-AD] RIN 2120
-AA64
AIRWORTHINESS DIRECTIVES; Teledyne Continental Motors (TCM) IO-520, TSIO
-520, and IO-550 Series Engines with Superior Air Parts, Inc. (SAP)
Cylinder Assemblies Installed
AGENCY: Federal Aviation Administration (FAA), Department of Transportat-
ion (DOT).
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) for
certain TCM IO-520, TSIO-520, and IO-550 reciprocating engines with
certain SAP cylinder assemblies installed. This proposed AD would require
initial and repetitive inspections and compression tests to detect cracks
in those cylinders with more than 750 flight hours time-in-service (TIS).
This proposed AD results from reports of cracks in the area of the exhaust
valve and separation of cylinder heads from the barrels of SAP cylinder
assemblies with certain part numbers. We are proposing this AD to prevent
separation of the cylinder head, which could result in immediate loss of
engine power, possible structural damage to the engine, and possible fire
in the engine compartment.
DATES: We must receive any comments on this proposed AD by June 10, 2008.
ADDRESSES: Use one of the following addresses to comment on this
proposed AD.
Federal eRulemaking Portal: Go to http://www.regulations.gov and follow
the instructions for sending your comments electronically.
Mail: Docket Management Facility, U.S. Department of Transportation, 1200
New Jersey Avenue SE., West Building Ground Floor, Room W12-140,
Washington, DC 20590-0001.
Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
Fax: (202) 493-2251.
FOR FURTHER INFORMATION CONTACT: Tausif Butt, Aerospace Engineer, Special
Certification Office, FAA, Rotorcraft Directorate, 2601 Meacham Blvd, Fort
Worth, TX 76137-4298; e-mail: tausif.butt@faa.gov; telephone (817) 222
-5195; fax (817) 222-5785.
SUPPLEMENTARY INFORMATION:
COMMENTS INVITED
We invite you to send us any written relevant data, views, or arguments
regarding this proposal. Send your comments to an address listed under
ADDRESSES. Include "Docket No. FAA-2007-0051; Directorate Identifier 2007
-NE-37-AD" in the subject line of your comments. We specifically invite
comments on the overall regulatory, economic, environmental, and energy
aspects of the proposed AD. We will consider all comments received by the
closing date and may amend the proposed AD in light of those comments.
We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact with
FAA personnel concerning this proposed AD.
Using the search function of the Web site, anyone can find and read the
comments in any of our dockets, including, if provided, the name of the
individual who sent the comment (or signed the comment on behalf of an
association, business, labor union, etc.). You may review the DOT's
complete Privacy Act Statement in the Federal Register published on April
11, 2000 (65 FR 19477-78).
EXAMINING THE AD DOCKET
You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Operations office between
9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD
docket contains this proposed AD, the regulatory evaluation, any comments
received, and other information. The street address for the Docket
Operations office (telephone (800) 647-5527) is the same as the Mail
address provided in the ADDRESSES section. Comments will be available in
the AD docket shortly after receipt.
DISCUSSION
Superior Air Parts and operators in the field have reported 24 SAP
cylinder assemblies with cracks or separation in the area of the exhaust
valves. Some instances resulted in forced landings of the airplanes. The
reported failures were cylinder assemblies in the naturally-aspirated and
turbocharged engines. Most of the failures were on airplanes that have a
high ratio of takeoffs and landings per flight hour. Most of the failures
also occurred on airplanes that are operated predominantly at low
altitude. SAP first informed us on July 12, 2006, that at least 14 SAP
investment cast cylinder assemblies, P/Ns SA52000-A1, SA52000-A20P,
SA52000-A21P, SA52000-A22P, SA52000-A23P, SA55000-A1, SA55000-A20P, had
cracked in the area of the exhaust valve of the cylinder head since the
year 2000. We received reports of 10 additional failures since that time,
and the total number of reported failures is currently 24. We determined
that the minimum wall thickness of the SAP cylinder assemblies, P/Ns
SA52000-A1, SA52000-A20P, SA52000-A21P, SA52000-A22P, SA52000-A23P,
SA55000-A1, SA55000-A20P, is significantly thinner in the failure location
than the original equipment manufacturer (OEM) cylinders. We certified the
SAP cylinders as equivalent replacement Parts Manufacturer Approval (PMA)
parts for TCM 520 and 550 series engines, however, this design discrepancy
results in stresses in the cylinder wall that are much higher in the SAP
cylinder assemblies than in the OEM cylinder assemblies when subjected to
identical loading. These higher stresses result in a lower fatigue life
for the SAP cylinder assemblies relative to that of the OEM parts. The
time-to-cracking or separation for this failure mode ranges between 823
hours time-since-new (TSN) and 1,985 TSN. The thin-wall thickness
condition in the area of the exhaust valve seat of the cylinder head has
been present since the initial SAP design, and it is present in all SAP
cylinders of that design that have been manufactured to date. This
condition, if not corrected, could result in immediate loss of engine
power, possible structural damage to the engine, and possible fire in the
engine compartment.
FAA'S DETERMINATION AND REQUIREMENTS OF THE PROPOSED AD
We have evaluated all pertinent information and identified an unsafe
condition that is likely to exist or develop on other products of this
same type design. We are proposing this AD, which would require inspecting
or replacing, or both, certain SAP cylinder assemblies within 25 flight
hours TIS after the effective date of the proposed AD for cylinders that
are at their respective time-before-overhaul (TBO) TIS flight hours or
have exceeded their respective TBO TIS flight hours.
COSTS OF COMPLIANCE
We estimate that this proposed AD could affect 8,000 engines installed on
airplanes of U.S. registry. We also estimate that it would take about 5
work-hours per cylinder to perform the proposed actions, and that the
average labor rate is $80 per work-hour. Required parts would cost about
$1,150 per cylinder. Based on these figures, we estimate the total cost of
the proposed AD to U.S. operators to be $12,400,000.
AUTHORITY FOR THIS RULEMAKING
Title 49 of the United States Code specifies the FAA's authority to issue
rules on aviation safety. Subtitle I, Section 106, describes the authority
of the FAA Administrator. Subtitle VII, Aviation Programs, describes in
more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in Subtitle
VII, Part A, Subpart III, Section 44701, "General requirements." Under
that section, Congress charges the FAA with promoting safe flight of civil
aircraft in air commerce by prescribing regulations for practices,
methods, and procedures the Administrator finds necessary for safety in
air commerce. This regulation is within the scope of that authority
because it addresses an unsafe condition that is likely to exist or
develop on products identified in this rulemaking action.
REGULATORY FINDINGS
We have determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD 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.
For the reasons discussed above, I certify that the proposed AD:
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. Would not have a significant economic impact, positive or negative, on
a substantial number of small entities under the criteria of the
Regulatory Flexibility Act.
We prepared a regulatory evaluation of the estimated costs to comply with
this proposed AD. You may get a copy of this summary at the address listed
under ADDRESSES.
LIST OF SUBJECTS IN 14 CFR PART 39
Air transportation, Aircraft, Aviation safety, Safety.
THE PROPOSED AMENDMENT
Under the authority delegated to me by the Administrator, the Federal
Aviation Administration proposes to amend 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. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive: