135 engine overhaul question

[Tug Driver]

Is there a time limitation (in years) along with TBO (piston engine) for part 135?

Ex: Baron 58 - zero time engines installed July 1993, do they have to be overhauled in July of 2005? Regardless of present engine hours?

 

[mike1mc]

The only limitation that exists is the manufacturer specified TBO (BE58 is 1700 hours). The props on the other hand are limited to 2000 hours OR 5 years (whichever is sooner).

This information is found in your Ops Specs paragraph D101. It should list the TBO for your engines, props, and governors as well a the appropriate maintenance document.

 

[bocefus]

Don't know about your particular TCM engine, but Lycomings do have a calendar time TBO (11 years) in addition to the hourly limit.

 

[kevin147]

The Engine has to be overhauled within the last 12 years for Part 135 operations.

If not, the overhaul will have to be done, regardless of current engine time.

 

[deadstick]

the winner is...

kevin147.

IAW TCM Service Information Letter 98-9A, the TBO is 1700 hrs OR 12 years.


"TCM recommends that the following information be used, along with the engine’s published TBO, in determining the engine’s continued airworthiness:

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1. Whether the engine has been operated regularly or has been in storage; gaskets, seals synthetic and natural rubber goods deteriorate over time. Environmental corrosion can occur internally and externally on the engine. This naturally occurring process can inevitably affect continued airworthiness of the engine and engine mounted components and accessories. For these reasons, overhaul the engine at least every twelve (12) years, or on accumulation of the operating hours listed for the engine model."

From what I understand, the 12-yr clock starts when the logs are signed for the installation on the aircraft. So, if the overhaul is signed off in January 2005, and the engines are not sold and installed until January 2006, then the overhauls are due, in the case of the IO-520-CB, at 1700 hrs OR January 2018.

 

[bocefus]

As mike1mc said, the answer to your question is in your ops spec, not with Lyc or TCM pubs. Ops spec can and often do deviate from the manufacturer's published TBO. I worked for a 135 operator that was allowed to go to 4000 hours TBO on the TCM IO-520 engines with a top overhaul at 2000 hours, this was in the op specs and contrary to TCM pubs.

 

[deadstick]

Ok, I'll buy that, bocefus. Some operators can do that with trend monitoring, a MORE program, or some other approved program. The operator I worked for didn't have any special program. We had to park a plane that timed out at 144 months with only 800/1000 hrs on the motors.

So, would it be correct to say that without an approved alternate mx program, just the "normal" operator has obey the manufacturers recommended times?

 

[bocefus]

Oh yeah, that would certainly be a correct statement. Tug driver was looking for a one size fits all answer and got a whole bunch that may or may not be applicable. So the answer to his original question of "Is there a time limitation (in years) along with TBO (piston engine) for part 135?". Yes, there will always be a calender time TBO along with an hourly limitation. To know the details, refer to your ops specs as they can and do vary and sometimes differ from the manufacturer's TBO limits.

 

[Tug Driver]

Thanks guys. That helps a ton.

 

[mike1mc]

kevin147.

For these reasons, overhaul the engine at least every twelve (12) years, or on accumulation of the operating hours listed for the engine model."

Thanks for posting that info guys. I had never heard that before. Of course I hope that you'll be flying a Baron more than 1700 hours in 12 years