Propeller Owner’s Manual
139
MAINTENANCE PRACTICES
61-00-39
Page 6-26
Rev. 17 Apr/20
(4) Installing nut plates (10-32 thread) of the type used to
attach the spinner dome will permit convenient balance
weight attachment on the engine side of the bulkhead.
(5) Alternatively, drilling holes for use with the AN3-( ) type
bolts with self-locking nuts is permitted.
(6) Chadwick-Helmuth Manual AW-9511-2, “The Smooth
Propeller”, specifies several generic bulkhead rework
procedures. These are permitted if they comply with the
conditions specified herein.
D. Placement of Balance Weights for Dynamic Balance
(1) The preferred method of attachment of dynamic balance
weights is to add the weights to the spinner bulkhead.
NOTE: Many spinner bulkheads have factory installed
self-locking nut plates provided for this
purpose.
(2) If the location of static balance weights has not been
altered, subsequent removal of the dynamic balance
weights will return the propeller to its original static
balance condition.
(3) Use only stainless or plated steel washers as dynamic
balance weights on the spinner bulkhead.
(4) A maximum of six AN970 style washers weighing up to
approximately 1.0 oz (28.0 g) may be installed at any
one location.
NOTE: The dimensions of an AN970 washer are:
ID 0.203 inch (5.16 mm), OD 0.875 inch
(22.23 mm), and thickness 0.063 inch
(1.59 mm).
(5) Install weights using aircraft quality #10-32 or AN-3( )
type screws or bolts.
(6) Balance weight screws attached to the spinner bulkhead
must protrude through the self-locking nuts or nut
plates a minimum of one thread and a maximum of four
threads.
NOTE: It may be necessary to alter the number
and/or location of static balance weights in
order to achieve dynamic balance.
