Can someone please explain me this A320 Starter Duty Limitation in simple terms?

E.g. for the CFM56 Starter:

No running engagement when N2>20%
4 cycles of max 2 mins
Pause between start attempts . . . . . . . . . . . . . . . . . .. . . . . . . . . 20 sec
Cooling period after 4 attempts . . . . . . . . . . . . . . . . . . . . . . . . . 15min

Does it mean the moment I put Engine Master to ON till Automatic abort by FADEC in case of Automatic Start or Manual abort by turning the engine master and man start button off (limiting it to 2 mins) in case of Manual start = 1 Cycle. Then 20 Seconds gap. Then Next Cycle and so on and then say after 4 unsuccessful cycles I got to wait for 15 min.

But things get confusing between words Cycle and attempt. Since for another type of Engine it says

Auto start with up to 3 start attempts is 1 cycle.
Between successive cycles – 20 seconds pause (for auto or manual ground starts).
After 4 failed cycles – 15 min cooling period.

What is attempt and what is cycle? I hope someone explains it in real simple terminology.


Some technical terms have universally agreed upon standard definitions. Others are ordinary words of the English language whose meaning must be discerned from the context. The words themselves are just labels, therefore it is less useful to debate their meaning and more important to understand the intent so that you can act appropriately.

To avoid confusion as in the seemingly contradictory examples you show above, I have typically seen starter limitations expressed in table format. This is how I would choose to depict the example above:

Start # Max time on Cool down
1 2 minutes 20 seconds
2 2 minutes 20 seconds
3 2 minutes 20 seconds
4 2 minutes 15 minutes

FWIW, I have heard these terms used interchangeably. Typically a normal start "cycle" begins when you engage the starter, and ends when RPM is at idle with oil pressure in band, and the starter has disengaged. If the engine never gets to that point it is a failed start "attempt". (or failed start cycle, or aborted start, or "try", or...)

I have never heard a series of failed attempts referred to as a cycle, but in the proper context the term would certainly be appropriate. Since the limitations are there to protect the starter, if RPM never gets above zero I wouldn't even count it as an attempt. Does this help?


Three start attempts are considered one "CYCLE" (we talk this in terms of starting the engine, that engine will get started in atleast these attempts). A gap of 20sec or 35 sec after each attempt (failed /successful) is required. And the cooling period of 15 min after 1 COMPLETE CYCLE (or 4 failed attempts) is required.

hope this helps.

  • $\begingroup$ Could you clarify if (i) between 'attempts' the starter remains engaged and motors the engine, and (ii) if the starter has to be reengaged (ie wait for N2<20%) then that constitutes a fresh cycle? Do you find sense in what I'm saying here? (I have no experience on type/engines.) $\endgroup$ – skipper44 Jan 2 at 19:08
  • $\begingroup$ This isn't how I have heard it defined... Do you have a source for this interpretation? $\endgroup$ – Michael Hall Jun 1 at 19:43
  • 1
    $\begingroup$ Re "Three start attempts are considered one "CYCLE"" and " And the cooling period of 15 min after 1 COMPLETE CYCLE (or 4 failed attempts) is required." -- This is confusing. Do you perhaps mean to say that "The cooling period of 15 min after 1 COMPLETE CYCLE (meaning 3 failed attempts) is required."? $\endgroup$ – quiet flyer Jun 2 at 17:56

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