FAA Issues ‘Concern Sheet’ On Continental IO-500-Series Engines


The FAA has issued an Airworthiness Concern Sheet (ACS) following up on a 2020 Airworthiness Directive (AD 2020-16-11) on Continental IO-500-series engines. The Oct. 25 ACS seeks input from operators on their experience with the effectiveness of compliance with the AD.

According to the ACS, “AD 2020-26-16 was issued as a terminating action; however, the FAA has received multiple reports from the field of cracked cylinders despite prior compliance with AD 2020-16-11. The FAA is concerned that the corrective action contained within AD 2020-16-11 is not sufficiently resolving the issue, so the FAA needs additional input from the field in order to better understand whether any additional actions are necessary at this time.”

The FAA asked, “Do you have (or did you have) a Continental GTSIO-520-C, D, H, K, L, M, N; IO-550-G, N, P, R; IOF550-N, P, R; TSIO-520-BE; TSIO-550-A, B, C, E, G, K, N and TSIOF-550-D, J, K, P engine with an affected cylinder(s) (whether the cylinder(s) is AD 2020-16-11 compliant or not)?” The agency then asked affected operators to report their aircraft type, engine model and the cylinder serial numbers “for each affected cylinder.” Operators are asked to respond within 30 days.

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Mark Phelps is a senior editor at AVweb. He is an instrument rated private pilot and former owner of a Grumman American AA1B and a V-tail Bonanza.

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  1. Wow, as best I can tell there were some bad parts, not the cylinders, that require inspection or replacement.

    You’d never know that from this AD. Of course, one can figure it out with a little research, but wouldn’t it be better to have in plainly spelled out in the AD in the first place?

  2. I read the AD a short time ago and what blew me away was compliance costs. Labor was listed at $80/hr. Talk about agency disconnect.

    Here in coastal california hourly shop rates are between $130-160/hr.

    Since usually 80%+ of AD compliance cost is the labor cost AD compliance expense numbers are greatly understated.

    Maybe the FAA could do a brief phone survey of shops in each geographical are and collect current shop rates. Last time I saw $80/hr was at least a decade ago.