Technical data

13773-001
74-20
Page 1
DISTRIBUTION
1. DESCRIPTION
This section describes the maintenance practices of that portion of the ignition system which conducts
high-voltage electricity from the magnetos to the spark plugs. For additional information pertaining to the
ignition harness and spark plugs, refer to the List of Publications in the front of this manual. (Refer to TCM
Ignition Systems Master Service Manual)
2. MAINTENANCE PRACTICES
A. Ignition Harness (See Figure 74-201)
(1) Removal - Ignition Harness
(a) Remove engine cowling. (Refer to 71-10)
CAUTION: To prevent damage to the spark plug insulator and connector, when with-
drawing insulator from spark plug, pull the harness lead straight out and at
same angle as the barrel.
(b) Remove ferrule assembly nuts securing ignition harness leads to spark plugs.
(c) Remove clamps and ties securing ignition harness to engine.
(d) Remove screws and nuts securing harness cap to magneto.
(e) Remove ignition harness from airplane.
(2) Installation - Ignition Harness
(a) Acquire necessary tools, equipment, and supplies.
Note: Prior to installing ignition harness, check mating surfaces for cleanliness.
(b) Attach ignition harness to the appropriate magneto.
(c) Install washers and screws securing harness cap to magneto. Torque screws 18 to 20
inch-pounds (1.98 to 2.2 Nm).
(d) Route ignition harness leads to the appropriate spark plug position as indicated by the
alphanumeric markings on each spark plug nut.
(e) Secure clamps and ties securing ignition harness to engine.
CAUTION: When tightening spark plug nut, hold ferrule with a 7/16” wrench to prevent
twisting the ignition lead.
(f) Coat insulator with Dow Corning 111 and insert into spark plug. Torque spark plug ferrule
assembly nut 110 to 120 inch-pounds (12.1 to 13.2 Nm).
(g) Install remaining insulators in accordance with (f).
(h) Install engine cowling. (Refer to 71-10)
Description P/N or Spec. Supplier Purpose
Dow Corning 111 DC 111 Any Source Lubricant and seal-
ant
30 Nov 2000