SERVICE
INSTRUCTION
652 Oliver Street
Williamsport,PA 17701 U.S.A.
717/323-6181
DATE:
October 6, 1978
SUBJECT:
Cleaning Fuel Injector Nozzles
MODELS AFFECTED:
Bendix
Model
RS and
Service Instruction No. 1275B
(Supersedes Service Instruction No. 1275A)
Engineering Aspects are
FAA (DER) Approved
RSA fuel injectors installed on Avco Lycoming
aircraft engines.
TIME OF COMPLIANCE:
As required.
Field reports have shown that solid particles carried by the fuel become lodged in the
fuel nozzles installed in the cylinders and
induction housings of applicable Avco Lycoming engines. This condition is indicated by
rough engine operation, uneven idle, cold
cylinders or unusually high fuel flow indication on the gage. Should these indications
occur after starting, run the engine about 2
minutes, shut down the engine and touch the
cylinders. A cold cylinder has localized the
problem.
ID of 0.080 inch. (For LW-14540 nozzles the
minimum ID of the supply should be 0.125
inch.)
NOTE
When any of these symptoms are found,
remove the nozzles and clean them with acetone or methyl-ethyl ketone and compressed air
as described in Bendix Energy Controls Division publication No. 15-541, "Air Bleed Nozzles Maintenance."
3. Nozzle flow shall be 32 phr. + 2 %. (For
LW-14540 nozzles flow shall be 57.5 to 59.5
phr.)
After cleaning, the nozzles should be tested for total fuel and air flow. The specifications for fuel flow are as follows:
1. Air test nozzle assemblies 74151, LW10476 and LW-10475 as shown in Figure 1. If
a nozzle assembly does not meet the requirements of Figure 1., recycle the assembly
through the cleaning cycle and retest before rejecting the assembly.
1. Connect the nozzle assembly to the test
stand using a supply line having a minimum
RUBBER
HOSE
The gage for measuring fuel inlet
pressure must be at the same height
or level as the nozzle.
(0.72. Test limits are based on naphtha
32/0.734 specific gravity at 700 /80°F.) at
an inlet pressure of 12 psi.
The specifications for air
follows:
HG
MANO
flow
are as
TEST REQUIREMENTS
WITH 14-16 INCHES HG AT
VACUUMSOURCETHE H20
MANOMETERSHALL NOT
EXCEED20 INCHESOF H20.
ATMOS
AIR
VACUUM
SOURCE
Figure 1. Air Testing Nozzle Assemblies
Page 1 of 2
Service Instruction No. 1275B
In normally aspirated engines where the
nozzles, P/N 74151 (Figure 1), are installed
horizontally, particular attention should be
paid to the identification marks stamped on
one of the hex flats on the nozzle body. This
mark is located 180° from the air bleed hole
and must appear in the lower side of the
nozzleto assure that the air bleed hole is on
top in order to reduce fuel bleeding from
this opening just after shutdown. To assure
nozzle is correctly torqued, tighten nozzle
to a little less than 60 in. lbs. torque,
continue to tighten until the letter or
number stamped on the hex of the nozzle body
points downward.
During the reassembly of nozzles P/N LW14540 or LW-11982 inspect packing ring for
possible damage or deterioration. If necessary replace with P/N LW-12081 packing ring.
Also use new lockplate P/N LW-11602 and
washer P/N STD-2173 if applicable (Figure 2)
when installing nozzles in induction housing.
Tighten nozzle to 15 ft. lbs. torque.
NOZZLE
SHIELD
TORQUE
60 IN.LBS.
P/N 74151NOZZLE
USEDINNORMALLY
ASPIRATED
ENGINES
(EXPLODED
VIEWTOSHOWPARTSONLY)
P/N LW-14540,P/N LW11982
NOZZLES
USEDIN TIOand TIGO-541ENGINES
Figure 2. Exploded View of Fuel Injection Nozzles
Nozzles P/N LW-10475 or LW-10476 (Figure 3)
are tightened to 60 in. lbs. torque. Replace
packing rings if they show any sign of damage
and deterioration. Also check the rubber hose
that connects the tube assembly of the nozzle
with the vent line for possible damage and
deterioration.
CAUTION
Do not immerse packing rings at anytime into the cleaning fluid. The
rings may swell.
TUBEASSEMBLY
TUBE
ASSEMBLY
P/N2525894
AIRBLEED
BODY
P/N2525892
AIRBLEEDBODY
P/N2521863
P/N2521863
SPRING
HOLDER
SPRINGHOLDER
SPRING
P/N2521864
PREFORMED
PACKING
P/N951391 TORQUE
60 IN.LBS.
P/NLW10475
NOZZLE
USED
ONTURBOCHARGED
ENGINES
PREFORMED
PACKING
60 IN.LBS.
TORQUE
P/N2521864
P/N2521864P/N LW10476NOZZLE
USEDONTURBOCHARGED
ENGINES
Figure 3. Exploded View of Air Bleed Nozzles
NOTE:
Revision "B" changes P/N LW-11980 to P/N LW-14540; adds to 1st paragragh; revises text;
adds Figure 1 and revises Figure 2 to add washer.
18867 - This number for Avco Lycoming reference only.
Page 2 of 2