The typical language for the TALON® cargo hook overhaul schedule, as found in either Instructions for Continued Airworthiness or the user’s manual, reads:
Time Between Overhaul (TBO): 1000 hours of external load operations or 5 years, whichever comes first.
To clarify the criteria related to TBO, Onboard Systems has drafted a letter explaining the conditions for tracking hours of external load operations. To summarize:
Hours of external load operations is defined as the time in which a helicopter is engaged in external load operations. This includes time between loads on the hook. For the purposes of TBO, hours of external load operations should be interpreted to be when:
- Anything is attached to the primary Cargo Hook—whether or not a useful load is being transported; and
- The aircraft is flying
If these two conditions are not met, time does not need to be tracked.
For users which do not exceed 1000 hours of external load operations in a five year period, TBO is five years from the date the cargo hook equipment was installed on the aircraft, whether or not the equipment is being used.