AIR FOR THE ENGINE START: FOLLOW ITS ROUTE
The lights can be on while the aircraft still lacks the air supply needed for a pneumatic start. Electricity and compressed air are different supplies. The engines, APU and an appropriate high-pressure ground connection can supply the pneumatic system, depending on the configuration. A ground-power cable is an electrical service; it does not provide start air. This distinction is useful when choosing ground services because two items may both be described casually as ground support while doing entirely different jobs. Ask what the equipment supplies, then find the aircraft indication that confirms it. [27, PDF pp. 2–4]
For an APU-assisted start, follow the air from the intended source towards the starter. The overhead selections establish the intended bleed and crossbleed arrangement. The crossbleed valve connects the two sides of the pneumatic system when required. Use ECAM BLEED to check that the actual valve and supply state supports the route you need. A selected source is one part of the arrangement, just as an available electrical source was one part of the power handover. If an engine-start preparation does not make sense, look along the complete path rather than adding unrelated switch selections. [27, PDF pp. 7–8] [28, PDF pp. 3–5]
The air-conditioning packs also use the pneumatic supply, so engine starting and cabin air conditioning are connected. Some valve actions occur automatically as part of the start sequence. Fenix V3 models selectable aircraft standards with different pack-closing timing. A pack-related change during the first engine's sequence may therefore differ from the behaviour you remember from another configured aircraft. Read it against the selected standard and the developing start. Afterwards, establish the normal air-supply arrangement for the next phase. A change in cabin-air sound is a reason to look at the sequence, not an instruction to immediately reverse the automatic action. [11, FADEC chapter: engine-start pack-inhibit standards] [28, PDF pp. 4–5]
At Frankfurt, trace one route before starting: the planned source, its bleed connection, the required crossbleed arrangement and the indication of usable supply. You do not need to memorise every pipe on the schematic to do this. Begin with the branch that matters for the current task. When the engine start changes the available sources, use the same diagram to understand what is supplying next. The pipes on the drawing then become a way to follow events rather than a page of decoration. [27, PDF pp. 7–8] [28, PDF pp. 3–5]
Engine bleed, APU BLEED and crossbleed controls. [23, PDF p. 1]
IN PRACTICE: Establish the start-air supply
Before you begin: APU AVAIL, aircraft secure and the normal APU-assisted start planned. This exercise establishes the supply path; the actual start is performed in the engine-start chapter.
1. Call the pneumatic picture
Action. Open the ECAM BLEED page and identify the APU branch, crossbleed connection, engine branches and pack indications. Compare their present states with the selected source.
Check. You can trace the air supply that will be used, rather than using electrical power as evidence that start air must also be available. [27, PDF p. 2] [29, PDF pp. 14-16]
2. Select APU bleed when required
Action. With the APU AVAIL, select APU BLEED for the planned task. Observe the indicated valve state and the associated duct information on BLEED.
Check. The selected APU source has a visible pneumatic path; APU availability and an open bleed-supply path have been checked separately. [27, PDF p. 7] [29, PDF pp. 14-16]
3. Check the crossbleed selection
Action. Check the normal X BLEED AUTO selection and the resulting valve indication for the APU-supplied state. Read the actual indication rather than treating a selector label alone as proof of valve position.
Check. The crossbleed path agrees with the selected supply and the applicable automatic logic. [27, PDF p. 8]
4. Review the receiving system
Action. Inspect the displayed pressure/temperature and any fault indications, then compare the supply with the engine-start requirements for the loaded aircraft. Keep pack and engine-bleed selections consistent with that procedure.
Check. The displayed path is suitable for the intended next task; a merely visible pressure value has not been adopted as a universal start limit. [27, PDF pp. 3-6] [29, PDF pp. 14-16] [13, PDF pp. 103-106]
5. Expect the installed start logic
Action. During the actual start, observe the pack/valve changes specified for the installed Fenix standard. V3 models more than one start pack-inhibit standard, so use its actual configuration rather than a universal PACKS OFF instruction.
Check. The observed sequence is compared with the chosen standard. Normal automatic changes are recognised instead of being countermanded without a reason. [11, Chapter FADEC] [30, Available Options: fnx_start_pack_inhibit_type]
Complete when: The intended pneumatic source and valve path are established and understood. Start readiness is then checked against the actual engine-start procedure.