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  #1  
Old 08-06-2021, 10:52 AM
erich weaver's Avatar
erich weaver erich weaver is offline
 
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Location: santa barbara, CA
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Default Which engine component overhauls are critical?

Hey guys

How critical do you believe it is to comply with recommended overhaul times for things like propeller governors and fuel injection systems, perhaps even constant speed props? I want to be safe of course, but Im hesitant to spend the money for the overhauls based strictly on calendar time. I fly regularly, but only about 50-60 hours a year and my prop governor (Jihostroj), fuel injection system (AFP) and prop (Whirlwind) are working fine. Moreover, Im not hearing about many catastrophic incidents due to failure to observe the recommended overhaul schedule. It seems to be fairly well accepted now that TBOs can be safely exceeded for engines when they are otherwise well maintained. What about these other components? Can I safely wait until I observe some symptoms of ill-health before sending them back to the manufacturer? In other words, dont fix what isnt broken?

I expect that more than a few of us let these TBOs slide, but that those that feel strongly that TBOs should be complied might be more likely to speak up on this forum. I would value the input from both sides of the issue.

thanks

Erich
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  #2  
Old 08-06-2021, 11:03 AM
lr172 lr172 is online now
 
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Location: Schaumburg, IL
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Quote:
Originally Posted by erich weaver View Post
Hey guys

How critical do you believe it is to comply with recommended overhaul times for things like propeller governors and fuel injection systems, perhaps even constant speed props? I want to be safe of course, but Im hesitant to spend the money for the overhauls based strictly on calendar time. I fly regularly, but only about 50-60 hours a year and my prop governor (Jihostroj), fuel injection system (AFP) and prop (Whirlwind) are working fine. Moreover, Im not hearing about many catastrophic incidents due to failure to observe the recommended overhaul schedule. It seems to be fairly well accepted now that TBOs can be safely exceeded for engines when they are otherwise well maintained. What about these other components? Can I safely wait until I observe some symptoms of ill-health before sending them back to the manufacturer? In other words, dont fix what isnt broken?

I expect that more than a few of us let these TBOs slide, but that those that feel strongly that TBOs should be complied might be more likely to speak up on this forum. I would value the input from both sides of the issue.

thanks

Erich
IMHO anything with rubber in it (FI components, fuel pumps, etc.) or with a possibility of corrosion (prop bearings/races) must have some element of age in the decision to inspect or overhaul. Recommendations may be conservative, but can't really ignore calendar time in those situations
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  #3  
Old 08-06-2021, 11:06 AM
Ralph Inkster Ralph Inkster is offline
 
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In the end, it's your butt. If you have a passenger, you have to consider THEIR butt too.

But also consider if your CofA is affected if you ignore basic overhaul time/hour requirements.

Mr. Insurance Guy may have a say also if there is a claim & he reviews maintenance records.
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  #4  
Old 08-06-2021, 11:25 AM
Taltruda Taltruda is offline
 
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If itís a rear mounted prop governor, you may want to overhaul it just to prevent having to pull it one day down the road while installed on the engine. Same with the mechanical FP, change it now while itís easy.
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  #5  
Old 08-06-2021, 11:53 AM
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rv8ch rv8ch is offline
 
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Quote:
Originally Posted by erich weaver View Post
... Moreover, Im not hearing about many catastrophic incidents due to failure to observe the recommended overhaul schedule. It seems to be fairly well accepted now that TBOs can be safely exceeded for engines when they are otherwise well maintained. What about these other components? Can I safely wait until I observe some symptoms of ill-health before sending them back to the manufacturer? In other words, dont fix what isnt broken? ...
Hi Erich, I think it's useful to think about the failure modes of these systems. Will they cause the engine to suddenly stop? Will you lose a blade, or will it go to full fine pitch? Will you get any warning before full failure? What will it cost to get these overhauled or an IRAN? People smarter than me suggest to just do what the manufacturer says, so if something goes wrong, you won't be kicking yourself if you have to land in a field or worse.

I think it's a topic worth investigating but getting real data will be hard. For example, you send in your prop governor for IRAN or overhaul, will they tell you exactly what they did? Can we find a way to log/document this someplace so others can see what happened? If the answer to both is yes, in a couple of years we might have an answer.

Or, we could push the suppliers to be more open with their reasoning for the IRAN/OH times and to share their statistics. What I have experienced is having a quiet conversation with a good prop shop or the supplier at a trade show often gets you some interesting information.
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  #6  
Old 08-06-2021, 12:34 PM
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erich weaver erich weaver is offline
 
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Quote:
Originally Posted by Ralph Inkster View Post
But also consider if your CofA is affected if you ignore basic overhaul time/hour requirements. Mr. Insurance Guy may have a say also if there is a claim & he reviews maintenance records.
Huh? None of this stuff is REQUIRED.
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  #7  
Old 08-06-2021, 01:10 PM
BlndRvtr BlndRvtr is offline
 
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Great question Erich.

While the concept of "If it ain't broke, don't fix it" certainly has merit, some things let you down at the most inconvenient time without warning and result in expense far in excess of preventative maintenance. I guess it depends largely on how and why you use the airplane.

Most recently I've been "educated" on the reason for traditional 500 hr magneto servicing. I wasn't stranded nor did it become a "safety of flight" situation, but it did cause an unplanned diversion and extra expense. Therefore I now appreciate and adhere to the manufacturers maintenance recommendations.

That newfound knowledge has also caused me to take a much harder look at modern electronic ignition systems. With regular 500hr service on traditional "tractor" mags not being cheap, long term the e-mag route is looking better and better. Now it's a decision on which one to get.

George
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