June 28, 2011
By Dan Namowitz
The FAA, declaring that an unsafe condition requires immediate action, will adopt a new airworthiness directive (AD) mandating inspection of some Lycoming and Teledyne Continental Motors (TCM) reciprocating engines with certain Hartzell Engine Technologies LLC (HET) turbochargers installed for debris from the machining process that could cause the turbochargers to seize.
Affected turbochargers with no more than 50 hours time in service on the effective date of the AD must be disassembled, and their center housing and rotating assembly (CHRA) cavities cleaned. This AD, which takes effect July 13, was prompted by a turbocharger failure due to machining debris left in the CHRA cavities during manufacture, the FAA said.
The problem “could lead to seizure of the turbocharger turbine, which could result in damage to the engine, and smoke in the airplane cabin,” said the notice of the AD.
“An unsafe condition exists that requires the immediate adoption of this AD,” the FAA said in its published notice of the AD. “The FAA has found that the risk to the flying public justifies waiving notice and comment prior to adoption of this rule because airplanes with no more than 50 hours time-in-service on new or overhauled affected turbochargers are at risk of the unsafe condition described in this AD. Therefore, we find that notice and opportunity for prior public comment are impracticable and that good cause exists for making this amendment effective in less than 30 days.”
This AD provides a table listing the Lycoming Engines and TCM engines to which the AD applies with Hartzell Engine Technologies, LLC (HET) turbocharger models TA3601, TAO401, TAO402, TAO411, TAO413, T1879, T18A21, T18A44, THO867, and TEO659 installed, as determined by serial numbers of the newly manufactured or rebuilt turbochargers.
The AD requires that affected turbochargers with zero to 10 hours time in service on the effective date of the AD be serviced as prescribed before further flight. For turbochargers with 10 to 50 hours time in service as of the AD’s effective date, required steps must be taken within the next 10 hours time in service. No action is required for affected turbochargers with more than 50 hours time in service as of that date.
No action was required for turbochargers with a circled “JT” foundry mark on the CHRA, or for engines with new or overhauled turbochargers installed on or before September 2001, the AD said.
The FAA estimated that about 2,761 turbochargers were installed on Lycoming and TCM engines on airplanes of U.S. registry, and that about 264 turbochargers would fail required inspections.
The AD will take effect July 13 because it addresses a critical safety-of-flight issue, but the FAA will accept comments by Aug. 12 on the proposal online, or by mail to U.S. Department of Transportation, Docket Operations, M–30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue, SE, Washington, D.C. 20590.
Dan Namowitz is an aviation writer and flight instructor. He has been a pilot since 1985 and an instructor since 1990.
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