The International Cessna^® 170 Association

AD Issued for TCM Reciprocating Engines
FAA issued an Emergency Airworthiness Directive (AD) on November 18, 2009, to address rapid wear with certain hydraulic lifters on Teledyne Continental Motors (TCM) 240, 360, 470, 520, and 550 series reciprocating engines. The AD requires replacement of these hydraulic lifters (P/Ns 657913, 657915, and 657916), if installed. TCM has reported three occurrences of rapid wear on the faces of these lifters with as few as five hours of time-in-service. If not corrected, airplanes using these lifters could experience a loss of power and control.
To view the AD, go to http://www.faa.gov/regulations_policies ... /emergency.

Regarding above AD:

(f) If your engine was manufactured or rebuilt before June 19, 2009, and you have not had any
hydraulic lifters replaced after June 19, 2009, no action is required.