Do airplanes have the equivalent of an odometer? How can one determine/prove how much use a plane has had?

Question

Do airplanes have the equivalent of an odometer? How can one determine/prove how much use a plane has had?

Answer 1

yes ..........they go by hours not miles

Answer 2

there is an hour indicator on the rpm dial.. in the middle.. they say a engine needs to rebuilt or overhauled at 2000 hours. if flown for hire.. and 3000 if used for other purposes.. ok but i have a conflict of opinion.. if the valves are good . good compression i leave it alone.. the older engines are ok. now a days every thing that is rebuilt fails some how..

Answer 3

This question can be broken into two parts, as you may have already read.  (I'm speaking from experience with smaller private aircraft, FYI.)  

There are two "odometers" or time-keeping devices in piston-driven aircraft.  One is the tachometer time, the other is Hobbs time.

I'll address tach time first.  As far as the airplane is concerned (operational requirements, maintenance intervals, what would be considered "miles" or usage of the airplane) tach time is referenced.  In piston-driven aircraft, the tachometer works exactly the same as in the car; it measures engine speed.  On aircraft tachometers, there is also a time counter.  This time counter runs in real time only when the engine is running at full operating capacity.  You can equate this to having the gas pedal of your car floored.  All entries made in aircraft maintenance logbooks reference tach time.

Hobbs time is run off the Hobbs meter.  Most all airplanes nowadays are equipped with one of these.  The Hobbs meter is a very simple time keeping device which is running anytime the electrical system of the airplane is on (in other words, when you turn on the master switch).  Pilots use Hobbs time to record flying experience in their logbooks.  PIlot logbook entries all reference Hobbs time.

Answer 4

To clarify on some of these answers, Hobbs time is based on actual time elapsed, not engine time.  The tach time is proper for actually knowing how much use the aircraft has had, as explained by whatwhathuh

Answer 5

Miles don't matter but hours do, particularly on the engine.  For this we use what's called a Hobbes meter that shows elapsed time.  Where it's hooked up depends, some use electricity (i.e. when the battery switch is on), some use oil pressure (engine(s) have to be running), some use airspeed, some are through the landing gear (so the gear has to be up).

There are cetain time compliance inspections that have to be accomplished and if operated for hire, airframe and engines can't be used over certain times.  I.e. 100 hour inspections on the airplane, TBO (time between overhaul) on the engines.

Answer 6

Most aircraft have a Tach Timer - which will measure the time the airplane is running in tenths of an hour.

The Tach timer is connected to the tachometer, which indicates how fast the engine and propeller are turning in revolutions per minute, just like your car.

This timer is set by the factory to be equal to normal clock time when the engine is at 2300 rpm (Piper) or 2400 rpm (Cessna). Therefore, when the engine is operating at low power levels, common during training, the Tach timer operates slower than clock time.

Some, mostly those available for rent, will also have Hobbes meters which is turned on when the master is turned on.

The times in the logbook for total time, TBO, etc. are tach time.

.

Answer 7

Some tachometers record cumulatively--in aviation (FAA publications) that is called an odometer.

Answer 8

In small, unpressurized aircraft wear and tear is usually measured in terms of hours of operation of the engine, the part of the aircraft that is most prone to wear and most in need of regular maintenance.  Large, pressurized aircraft such as jet airliners measure engine hours, too, but also count the number of take-off and landing cycles, or, more specifically, the number of pressurization cycles, as these cycles put wear and tear on the airframe.  Some other measured parameters include take-offs and landings for tire wear and airframe acceleration stresses to take into account wear and tear from hard landings and turbulence.

In other words, different parts of an airplane are measured for wear and tear in different ways, so there's no exactly equivalent of an automobile odometer.  In fact, total miles traveled is almost irrelevant in aircraft, as simply moving through the air doesn't produce much wear in most cases (for supersonic flight, however, the situation is different).

Answer 9

They have a Hobbs meter, that measures hours an engine has been run.