Hartzell HC-E4 3 Series Owner's Manual page 38

(4) When a component or assembly undergoes an overhaul,
the TSO is returned to zero hours.
(a) Time Since New (TSN) can never be returned to
zero.
(b) Repair without overhaul does not affect TSO or TSN.
(5) Blades and hubs are sometimes replaced while in
service or at overhaul.
(a) Maintaining separate TSN and TSO histories for a
replacement hub or blade is required.
(b) Hub replacement
1 If the hub is replaced, the replacement hub serial
number must be recorded (the entry signed and
dated) in the propeller logbook.
2 The propeller will be identified with the serial
number of the replacement hub.
NOTE:
3 The TSN and TSO of the replacement hub must
be recorded and maintained in the propeller
logbook.
4 If tracking any component(s) other than the
hub/blades, maintain these TSN/TSO records
separately in the propeller logbook.
NOTE:
INTRODUCTION
Propeller Owner's Manual
147
Propeller assembly serial numbers
are impression stamped on the hub.
For stamping information, refer to
the Parts Identification and Marking
chapter of Hartzell Propeller Inc.
Standard Practices Manual 202A
(61-01-02).
Hub replacement does not affect
the TSN/TSO of any other propeller
components.
61-00-47
Page 1-12
Rev. 16 May/20