Hobbs or Tach Hours

LauraE51

Pre-takeoff checklist
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Laura
Greetings

I'm curious which, the Hobbs meter or the Tachometer, are used to determine 100 hour inspections and time SMOH.

thank you in advance.

Brian
 
Our club aircraft do not have Hobbs meters installed. So we go by tach hours.
 
The club I'm in goes by tach, even though they have both tach and Hobbs.
 
Since you are talking 100 hours I'm guessing you are talking about a rental plane used for hire. Every FBO I've flown at went off Tach time for inspections. Gave them more time between inspections.
 
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For a piston, all the mx hourly stuff is off tach.
 
That's what I've seen too, rental is charged by hobbs hour, and mx per the tach hour.

Since you are talking 100 hours I'm guessing you are talking about a rental plane. Every FBO I've flown at went off Tach time for inspections. Gave them more time between inspections.
 
If it earns money, go by hobbs. If it costs money, go by tach. Isn't that why we have both? :)
 
The definition of time in service for an aircraft is essentially the time that is in the air (which is the maintenance time for things like 100 hour). The FAA will allow just about any approximation of that as long as you're consistent. Most people do use the tachometer as time in service. My plane doesn't have a recording tach. The hobbs is connected to the landing gear so it is much closer to the FAA definition than most.
 
Since you are talking 100 hours I'm guessing you are talking about a rental plane. Every FBO I've flown at went off Tach time for inspections. Gave them more time between inspections.

Part 91 rental planes do not require 100 hour inspections unless they are used in training.
 
Part 91 rental planes do not require 100 hour inspections unless they are used in training.

Since you are talking 100 hours I'm guessing you are talking about a rental plane used for hire. Every FBO I've flown at went off Tach time for inspections. Gave them more time between inspections.

FIFY...
 

No, renting aircraft under part 91 is not considered "for hire." For hire would be air taxi or charter operations under part 135 or scheduled airline operations under part 121.
 
No, renting aircraft under part 91 is not considered "for hire." For hire would be air taxi or charter operations under part 135 or scheduled airline operations under part 121.

I think Gucci's point is that we can safely assume the aircraft is being used at least part time for hire as the OP probably wouldn't be asking about 100 hour inspections unless the operator of the aircraft was doing them.

Most of the rental places I know do 100 hours: instruction is part of their business and the added flexibility of being able to use all the aircraft in their fleet for instruction rather than just a few offsets the added cost of 100 hours. I'd imagine that the provision for not doing 100 hours is most often exercised by cooperative ownership arrangements and flight clubs that are set up as independent companies, friends lending aircraft, and the like.
 
I think Gucci's point is that we can safely assume the aircraft is being used at least part time for hire as the OP probably wouldn't be asking about 100 hour inspections unless the operator of the aircraft was doing them.

Most of the rental places I know do 100 hours: instruction is part of their business and the added flexibility of being able to use all the aircraft in their fleet for instruction rather than just a few offsets the added cost of 100 hours. I'd imagine that the provision for not doing 100 hours is most often exercised by cooperative ownership arrangements and flight clubs that are set up as independent companies, friends lending aircraft, and the like.

Thank you!

No, renting aircraft under part 91 is not considered "for hire." For hire would be air taxi or charter operations under part 135 or scheduled airline operations under part 121.

True. Assuming there are rental planes out there that advertise "not available for flight instruction". Which I'm sure the number is slim to none. Willing to bet you would need to be checked out in said aircraft for insurance purposes, which would require a flight instructor of that FBO, and also a 100 hour inspection on the aircraft. You can do "for hire" under part 91. Flight instruction and Aerial Photography come to mind.

FAR 91.409 (b) Except as provided in paragraph (c) of this section, no person may operate an aircraft carrying any person (other than a crewmember) for hire, and no person may give flight instruction for hire in an aircraft which that person provides, unless within the preceding 100 hours of time in service the aircraft has received an annual or 100-hour inspection and been approved for return to service in accordance with part 43 of this chapter or has received an inspection for the issuance of an airworthiness certificate in accordance with part 21 of this chapter. The 100-hour limitation may be exceeded by not more than 10 hours while en route to reach a place where the inspection can be done. The excess time used to reach a place where the inspection can be done must be included in computing the next 100 hours of time in service.
 
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You can also get out of doing 100hr inspections if the student rents the plane but provides his own instructor who is not employed/recommended by the school, and the student is free to bring in any CFI he wishes.

Thus plane and crew are not provided by same entity = not for hire.
 
You can also get out of doing 100hr inspections if the student rents the plane but provides his own instructor who is not employed/recommended by the school, and the student is free to bring in any CFI he wishes.

Thus plane and crew are not provided by same entity = not for hire.

Very true, but that is rarely allowed by a flight school or the insurance carrier
 
Overhaul time go by tach. Logging hours go by Hobbs.
 
Overhaul time go by tach. Logging hours go by Hobbs.

While that is a commonly done NEITHER is the definition of the times for those.

For maintenance (Overhaul, 100 hours, AD compliance) the time is Time In Service and is defined as:

Time in service, with respect to maintenance time records, means the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing​

For pilot logging, the time is Flight Time, defined as:

Flight time means:

(1) Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing; or

(2) For a glider without self-launch capability, pilot time that commences when the glider is towed for the purpose of flight and ends when the glider comes to rest after landing.​

The FAA doesn't really care what you use for either one as long as you are reasonably consistent. Many planes don't have hobbs meters. Some planes (like mine, and many later model Bonanzas) don't have recording tachs.
 
Thank you!



True. Assuming there are rental planes out there that advertise "not available for flight instruction". Which I'm sure the number is slim to none. Willing to bet you would need to be checked out in said aircraft for insurance purposes, which would require a flight instructor of that FBO, and also a 100 hour inspection on the aircraft. You can do "for hire" under part 91. Flight instruction and Aerial Photography come to mind...
You are mistaken. I've seen many outfits that have several aircraft on the line for rental only. Some are leasebacks that the owner stipulates he doesn't want used for training. Some require rental insurance. Aircraft checkouts are not instructional flights per se. The purpose of the checkout is to verify you are competent to fly the aircraft, not to teach you to fly the aircraft. Plenty of owners out there rent out their aircraft to trusted friends, not so much to make money but to put some hours on otherwise unused hardware.
 
You'd have a hard time convincing me or the FAA that forcing me to drag your instructor along (for what ever reason) doesn't qualify as flight instruction under the 100-hour rule.

Actually, I've more often seen DUAL ONLY restrictions on aircraft by owners than I've seen "no flight instruction" requests.

Besides, aircraft at FBOs that are NOT used for flight instruction, rarely fly enough to get 100 hours in before the annual is due anyhow (and hence rarely are profitable).

In fact, our club NEVER did 100 hours technically. We just did an annual inspection more often than once a year :)
 
You are mistaken.

No I'm not. I know what the rules say and when a 100 hour is or isn't required.

Aircraft checkouts are not instructional flights per se.

Willing to bet an FBO is gonna ask you to fly with one of their CFIs for the checkout. I'm sure he isn't gonna do it for free. Try telling the FAA that isn't for hire. Doesn't matter if the CFI is sitting there asleep, he's there, and he's getting paid.

Plenty of owners out there rent out their aircraft to trusted friends, not so much to make money but to put some hours on otherwise unused hardware.

That's true. And those wouldn't require a 100 hour. The OP didn't say it but I don't think he is renting the airplane from a friend. The plane he is talking about obviously has 100 hours performed or he wouldn't be asking about it.


Anyways, this is getting WAY off topic from the simple question that was asked.
 
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