A320 Why do lot of pilots start chrono while starting engines?
 

I have seen a lot of pilots start chrono while starting the engine in A320.

It is not mentioned in the SOP anywhere and I couldn't find its utility.

Any good reason to do that?

There will be a limit for starter usage.

Are you asking about the first flight of the day (or if 2 hours passed since the previous flight), or in general? Just curious.

On the IAE engines we're looking for ignition on after 30 seconds, these engines have a dry crank first and take longer to start than the CFM ones.

Starting the chromo while starting the engines is a TECHNIQUE, not an SOP. The rational is that if you have a start abort and subsequently have to complete a dry crank and or manual start, it is the only way of monitoring the amount of time you have had the Start Valve Open with respect to the Engine Starter Limitations.
Other people can argue the validity of this technique.

After start, after a shut down period greater than 2hrs, to avoid thermal shock, the pilot should operate the engine at or near idle for at least 5min before advancing the thrust levers to high power (above 40% N1). That is SOP.

After start it is for that reason.

On the CFM, you have 15 sec maximum after you got the fuel flow to get an N1 and EGT increase.
Most people start the timer once the ignition starts, which makes no sense.
It is not SOP as everything is controlled by the FADEC and in case of a manual engine start the sequence is not the same (first you reach maxi motoring speed then you put the eng master on).

The starter time limit is observed by FADEC. For manual start, there will be an ECAM warning.

We tap the chrono to comply with a company 3 minute warm up requirement. We also do the same on landing for single engine taxi.

It’s probably a hangover from the old days of Instrument Rating Renewals where you got bonus points for starting your stopwatch as many times as possible during the detail... ;)

Not in the SOP's but it is mainly to respect the 2' idle thrust before taxiing. But it is also helpful to monitor the starting sequence of the engine. Beside that in case of a manual start it is SOP's

Isn't it a Boeing CFM thing?
mcdhu

It is completely irrelevant but stems from the starter limit which ECAM covers anyway. Lots of things still done which are a hangover form the old days. ;)

I don't because I see no practical benefit. I know I can attempt a start, dry crank, and second try without exceeding the starter time limit.

If it hasn't started by that point you can guarantee that I want engineering input before trying again.

Our ECAM can't measure consecutive start attempts.

Our limitations: 2 mins on, 15 secs off, 2 mins on, 15 secs off, 1 min on 30 mins off. So in the unlikely event you get to the third start, does you ECAM 'Know' that this is your third start attempt? We have pretty old -320's so maybe the newer ones are smarter.

Engine warm up for our engines is measured from 'at or near idle.' There fore we hack the clock when the starter valve opens then re hack after the second engine is at or very nearly stabilized at idle.

So many versions of a very good airplane flying around, what I just described is how we operate in our little world....

If you have to do a manual start the procedures state that the start be timed. I do it on a normal start so that I know if there is no light off by 45 seconds then there is a good chance that the next sound I here will be a MCW chime. This takes out the startle factor and I can start thinking about letting ATC know that we are going to be on the taxiway a bit longer than they may be anticipating. As someone stated, technique not SOP.

You can exceed the 2 min mark on the crank time with high residual EGT prior to ignition and an aborted start.... It also makes me feel like I have some input without touching something I shouldn't... Unless directed by ECAM :p

If you need to crank with a tailpipe fire you can do it for as long as you like. Noting the time helps engineering decide what to do with the starter unit afterwards.

Starter damage is much cheaper than engine damage.

It could simply be for one's own situational awareness.

Our CFMs should light up within 10 seconds, if not, we place the start lever to cut off.
It will automatically cut fuel if no light up within 15 seconds.
The 10 seconds rule is why I time the start.
It doesn't hurt.

Two people have now mentioned two hours since the previous flight. Is this an IAE limitation? It's a while since I flew aircraft with IAE engines, so it may well have slipped my mind. The magic number for CFM seems to be six hours: if the time elapsed since the previous flight is more than six hours, we can't do single engine taxi, and engines must be at idle for at least five minutes before applying take off thrust.

Yep, after two hours, 5 min warmup req for V2500.

Since we're here.

IAE warm up less than two hours is 2 minutes. I just heard a theory that it isn't really for the warmup but to ensure the center tanks pump check is complete after second engine start and before take off. Any body else hear this?

(BTW, I just had this happen, last week. At the gate told FO to shut down #2, he does, it does't shut down! What do I do - what any Captain would do, try it again with the engine master, the third time I figured there was a problem and referenced the non-normal. I had to use the ENG Fire switch to shut the damn thing down, so yes that can happen)

The IAE warm up is for thermal equalisation and to prevent shaft bowing.

Common when the DC ESS BUS has a hiccup, ENG MSTR SW is gone burger, or the Engines fuel HP valve isn't interested either.

ENG FIRE P/B (no bottle). All associated valves will reset once the switch is pushed back in. Aside from the engineering questions prior to resetting, of course.

Does anyone know if the accessory gearbox is still turning below 18% N2?

Tubby's post is basically correct except for the fact that shaft bowing has probably already occurred by the engine sitting without the shafts turning. Think of a dumbbell with heavy weights on both ends (fan & booster ---- LPT).

Although the engine dynamics are even more complex, here is a simple explanation of the IAE situation. Shortly after engine shutdown, heat begins to build up in the top portion of the engine due to the heat retained in the engine components and lack of venting for this trapped heat. This so-called "chimney effect" can deflect (bow) the low and high-pressure shafts due to the diametral temperature gradient. The maximum deflection generally occurs between 1 to 2 hours after engine shutdown. Therefore, if an aircraft's engines are restarted during that period, a bowed rotor start can occur that could create a rub condition along with rotor dynamic issues. Bowed rotor starts have been known to actually lockup the low-pressure shaft due to the LPT blade interference with the LPT shroud. By keeping the rotational speeds as low as possible for a period of time at idle speed, both the rotors and stationary components have a chance to stabilize which helps preserve clearances and therefore engine efficiency.

Hope this helps...

Sure "it doesn't hurt." But where do you stop with that sort of philosophy? For instance you can conduct a walk-around pre-flight inspection while whistling Dixie. It doesn't hurt :E

CaptainMongoAFAIR after the Qantas A380's uncontained failure of #2, after they landed #1 wouldn't stop until the fire people drowned it with water and foam.

Ah, no not every Captain. I hope you had a look at what position the LP valve was in before you reached for the fire switch!

Lookleft, interesting point, however the advice I have is 4-7 minutes before the engine shuts down in that scenario.

Curious as to why one shouldn't use ENG FIRE P/B in this scenario because honestly, I can't think of a reason one wouldn't. Of course this doesn't mean there isn't.

Because the Supp Proc in FCOM tells you to only shut down using the ENG FIRE pb if the LP fuel valve is not closed. By using the ENG FIRE you have now disconnected a whole bunch of other systems including FADEC. Now engineering will need to attend the aircraft,which if you are not at an engineering port becomes an issue that could have been avoided if the engine was allowed to shut down normally albeit a little bit longer than normal.

Still, better than sucking a loadie through it.

The loadies should know that if I am parked at the gate with the beacon on then they shouldn't be anywhere near where they can be sucked into the intake. Its not much of an excuse when the CP asks me why I didn't follow FCOM.

Should, yes. Always do, no.

Does the FCOM cater for "idiot walking towards engine"?

Too many people have gone down an engine and have come out the back in tiny pieces. I think your CP would be OK with you shutting down an engine by any means possible to avoid another one.

My CP would be ok with it if I observed or was told that the idiot was about to go in the blender but they would not be ok with me using non-FCOM procedures on the possibility that an idiot just might or I thought there might be a slight chance of an idiot going through the blender. There is only so far that the PIC can idiot proof his/her operation and still stay within the rules.

Hi lookleft, thanks for the reply. Fair point. That why we are Captains. We sometimes make decision based on knowledge, and sometimes it is just experience and skill. Not all are in FCOM as you know, and the circumstance would always dictate as you say.

If the engine doesn't shutdown you will still need engineering to attend because the HP valve is stuck open/and or ENG MASTER S/W is Unservicable. One is not going anywhere :)

Lookleft,


If you would have read my post, you would have read that I followed the non-normal procedure (Engine fails to shut down) after cycling the engine master. I think cycling the engine master was a reasonable response since I had in my right seat a pilot who just came out of our training center, was on his first flight and this was the first time he ever operated the engine master in the airplane. But hey, what do I know, I only have been doing this flying thing for 34 years.

While we're at it, whilst transitioning to manual flight why do some people insist on frantically pressing the takeover PB to disconnect the AP? Surely once to disconnect then once to silence to Calvary charge is enough? Just two clicks is all you need. Some people I've seen literally press it 10/20 times. I thought this clock starting was all a hangover from the Boeing days.

Chesty, serious question. Given the number of aircraft movements in a day/week/year across the globe, and the number of people who as you say have gone down the front of an engine and out the back in pieces, do you really think it is a risk worth inventing ad hoc procedures for?

I suspect that taking a couple of extra minutes to evaluate the system state, have a quick glance at the supp proc if necessary and then have a bit of a think about the ramifications of any subsequent action would be a wise investment.

I get the sense that we, as pilots, often tend to focus on things that we perceive to be significant threats that when reviewed in the cold hard light of day are very low probability events (even if they do have a significant consequence).

This is, in part, ingrained in us from the very beginning. When you think back to pretty much any training there is a big focus on engine failures, seizures, fires etc but if you did a training matrix based on real world threats you might shift the focus to things such as two engine go arounds, unstable approaches etc, particularly if you reviewed the statistics surrounding the number of movements vs number of engine failures/fires/severe damage and compared them to things like movements vs TCAS RA's, unstable approaches, cocked up two engine go arounds etc.

Just a thought :) and definitely not a criticism

If you can't shut down an engine using the normal cut off procedure and you see a ground guy heading towards that engine, or even near it, giving you seconds to make a decision why would you not pull the fire handle?

It isn't a made up procedure it is a valid way of shutting down an engine.

If you have a look at PRO-SUP-70 no you didn't! The procedure states that if the LP valve is closed-cross line amber then no crew action is required. Cycling the Eng master 3 times is not in the procedure!

All you did was demonstrate what not to do when faced with a situation that Airbus has already covered in FCOM. What happens when young Bloggs comes up for his/her check ride and the Check Captain saids "What would we do if we set the eng master to off and the engine didn't shutdown?" Bloggs confident in his/her response would say,"I've seen this before, I would cycle the eng master 3 times then push the ENG Fire switch!" The Checkie would then say, "Wrong Bloggs, we would look at FCOM Sup Proc and do what Airbus tells us to do."

Bula- The ENG MASTER switch operates the LP valve. The FCOM procedure states that if the LP valve is amber cross line then no crew action is required. This means that the master switch has done its job and you are just waiting for the fuel in the lines to make its way through the engine. If the LP valve line is still green then the master has not done its job then you use the ENG FIRE pb to force the LP valve to close. According to FCOM the time delay can take up to 2min30s which can seem like an eternity when you are waiting for something to happen. It also states "Keep ground staff informed" which is a nicer way of saying don't let the idiots get near the blender.:ok: