Valves; Valve Springs - Rotax 912 Series Maintenance Manual

14.5.4)
14.5.5)
1
fig. 167
00283
Effectivity: 912 Series
AIRCRAFT ENGINES
MAINTENANCE MANUAL II

Valves

See fig. 166.
Clean valves and check valve head Q for wear. Place valve on V-blocks
W, roll them for checking out-of-true with dial gauge (max. admissible out-
of-true, measured on valve head, see dimension ] in para 15.
The sealing surface on the
valve head is armoured
and must not be reworked,
seal-lapping by emery
paste is allowed only, see
para 11.7.16. Renew valve
as necessary. Minimum
rim thickness R of the
valve head is 1,2 mm
(0,047 in.). Check holding
grooves T on valve stem.
Check valve cotters, re-
place as necessary.
The thermal stress is higher on the exhaust valves (dia. 32 mm = 1,3 in.)
therefore direct special attention when checking this valve. Seal-lap both
valves and check for leakage.

Valve springs

See fig. 167 and 168.
One spring retainer per valve is used. The spring Q got a wire gage of 3,85
mm (0,15 in). The same springs are on inlet and exhaust valves. Spring
rate non progressive. Visually check springs for fracture and deformation.
1 2 3 4 5 6 7
Maß
dim.
Check free length of both springs, see dimension A in para
A
15. Renew valves shorter than the minimum length.
NOTE: In design year 1997 the single spring retainer was
introduced, see SI-14-97.
NOTE: Actual spring length should be as equal as possible, on
inlet and outlet side. Renew as required.
Dimensions
See Wear Limits in para 15.
00284
2
fig. 166
8 9 10 11 12 13 14 15 16
00282
New
3
1
4
1,2 mm
0,472 in.
17 18 19 20
fig. 168
Wear limits
page 106
Initial issue, Jan. 01/2002