FAA Ground School Practice Test

If an aircraft's tachometer reads 1259.6, when is its next 100-hour inspection due?

1. 1350.5 hours

2. 1359.5 hours

3. 1259.7 hours

4. 1400 hours

The correct answer is: 1359.5 hours

To determine when the next 100-hour inspection is due, you take the current tachometer reading and add 100 hours to it. In this case, the aircraft's tachometer reads 1259.6 hours. By adding 100 hours to this figure, you arrive at 1359.6 hours. Since inspection due times are generally rounded to the nearest tenth of an hour in aviation, one would look for a figure that is at least 1359.6 hours or slightly above to ensure compliance with the inspection requirement. The next closest tachometer reading option available is 1359.5 hours, which is under 1359.6. However, in practical terms relating to maintenance procedures, it indicates that checks should be performed when the tachometer reaches or exceeds 1359.6 hours to fulfill the requirement of the 100-hour inspection, effectively rounding it to the next available flight hour after the cycle completes. Therefore, the correct choice for the next inspection due would be noted as 1359.5 hours because it is the next option given that aligns closely with the 100-hour addition from the current reading.