22
SAFIR 5L
OPERATION AND ATTENDANCE MANUAL
PG 01-31
3.
OPERATIVE LIMITS
Actuation Repeatability
After APU shutdown, its next actuation can begin after 60 sec. The number of such actuations is limited till 3, it can
be actuate for the 4 time firstly after 20 minutes on the ground, or after 10 minutes in the air.
In emergency situations, the second start of APU can be repeated without delay. Number of starts repeated without
delay is limited to 20 in period before the periodic inspection. The user must record these without delay repeated
starts into the APU Engine log book.
Note: It is recommended to observe the minimum interval of 40 sec. between switching APU off and a new start.
This time must be observed to ensure the fuel draining from the combustion chamber and fuel ramp.
When starting APU actuation can be repeated with 2 minute pause after unsuccessful start caused by failure to
ignite the combustion chamber (APU shuts off after 13 sec.). These unsuccessful starts must be recorded by the user
into the APU Engine log book. Their number is limited to 20 in period before the periodic inspection.
Low Temperature Operation
The manufacturer guarantees APU start and operation at the lowest ambient temperature of –60
o
C (-76
o
F) on the
prerequisite that no part of the oil and fuel loop is subcooled to less than –40
o
C (-40
o
F). Before actuating APU at
temperatures below –40
o
C (-40
o
F) on the ground, when there is a possibility that some parts of the fuel and oil loop
reach the same temperature, it is recommended to perform warming up of the area of APU location by the means of
warm air with temperature amounting to 80
o
C (176
o
F) max. for 30 minutes.
Power Supplies
A 24 V – 28 Ah battery with minimum capacity of 75 % of its nominal value or other battery supply with the same
voltage and minimum power supply.
Electric voltage on the connector of electric-starter
must be from 14 to 26 V during APU starting ! ! !
The 4 starts can be performed with above mentioned battery source.
Compressor Protection
The operating organization of the actuating unit must ensure the cleanliness of the suction area of the APU
compressor ! ! !
In case of penetration of some foreign matter or rough junk, there is a danger of damaging the compressor blades
and, as a result, outage of APU.
Also suction of exhaust gases, whether they originate from APU or from other source, is prohibited ! ! !
Control System Protection
Control box ensures the shutdown or speed reduction of APU after having attained parameters stated in Article 1.5.
Air Intake Limits (in 100 % Mode)
- minimum air intake is not limited
- maximum air intake is limited by Venturi tube ø33
