Trent_800
Topic Author
Posts: 136
Joined: Thu Jan 03, 2002 11:29 pm

Hot Start On Engines, What Next?

Sun Mar 31, 2002 9:44 pm

When starting a Engine up and the crew notice that the fuel flow is above normal and the EGT keeps rising and rising the pilot cuts the fuel flow to the engine to prevent a meltdown. My question is what happens next? Does the pilot let the engine settle and try to start it again or does one would-be hot start warrant the engineers to be called in?
 
Bjones
Posts: 122
Joined: Sat Feb 16, 2002 11:46 am

RE: Hot Start On Engines, What Next?

Mon Apr 01, 2002 12:18 am

It really depends on a lot of things. How hot it got (were any limits exceeded), what aircraft/engine you have, why you think it got hot. In some aircraft there are certain things that contribute to hot starts that can be compensated for. For instance some small jets with electric starter motors instead of air starts might have a weak battery which caused a slow spool up, this could be remedied by using an APU. In other cases the hot start might be due to a hot day with a wind blowing the exhaust gas back up the tail pipe. Or of course it could be a aircraft malfunction. Typically if you exceed any operating limitations or see something such as very rapid ITT or EGT(depending on acft type) rise its time for maintenance to look at the aircraft the first time.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Mon Apr 01, 2002 4:12 am

A generic QRH procedure would be, for a rapidly rising EGT/ITT (or Turbine inlet temp, whatever is specified for the particular engine):

1. Abort the start; if ITT remains high,
2. Dry motor the engine
3. If a temp limit was exceeded, call maint for an inspection or additional procedures

If temp limits weren't exceeded, and after the engine has been motored, another start attempt is typically OK.

Finally, it's hard gauge a start by monitoring fuel flow, as it will vary with atmospheric conditions and the rate at which the engine accelerates. Generally EGT is the primary parameter, with N1, oil pressure, ignitors, and fuel flow all being secondary to temp.
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: Hot Start On Engines, What Next?

Tue Apr 02, 2002 2:30 am

Typically, a hot start will be preceded by abnormally very high fuel flow when the fuel lever (switch) is raised.

You're only as good as your last departure.
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Hot Start On Engines, What Next?

Tue Apr 02, 2002 1:47 pm

Fuel flow is your first indication of a possible hot start. I'm not saying you're going to get one, but I typically watch a little closer to prevent the hot start.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Tue Apr 02, 2002 2:08 pm

I don't agree...I've never seen a max fuel flow limitation as part of a start procedure. Fuel flow will vary with atmospheric conditions, whether its a mechanical fuel control or FADEC equipped.

From the above viewpoint, if a rapidly rising fuel flow is the "first indication of a possible hot start", and the resulting start is normal, then what value is fuel flow as a first indication? It's not; EGT is.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Tue Apr 02, 2002 2:13 pm

A hot start can also be preceded by a slower than usual N1 acceleration, but again the primary parameter is egt.
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Hot Start On Engines, What Next?

Tue Apr 02, 2002 3:21 pm

There is a specified fuel flow range for engine start. The JT9D-7AH's range is 600 - 800 pph. Anything above 800 pph should be viewed as having the possibility of a hot start.

 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 03, 2002 12:52 am

Every gas turbine has a range of normal startup parameters from oil pressure to vibes to N1, N2 etc.
What does "anything above 800 lbs/hr should be viewed as having the possibility" mean? That doesn't sound like a limitation...

Fuel flow is a secondary, not the primary or "first" indication of a hot start.
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: Hot Start On Engines, What Next?

Wed Apr 03, 2002 12:53 pm

A300/310 Run/Taxi Study Guide

Hot Start (A300-600 w/GE CF6-80
A hot start can be anticipated by observing an initial fuel flow greater than normal (greater than 700 pounds/hour) at the instant the HP fuel lever is placed in the position. After light off, fuel flow will rise as needed to accelerate the engine to idle RPM. Normally this will be about 1600 PPH peak but will vary depending on weather conditions.

If hot start occurs, terminate starting cycle immediately by returning HP fuel lever to OFF position. Continue motoring engine to reduce EGT below 180 degrees C. If light off did not occur spool engine for 30 seconds to purge engine of excess fuel.

CAUTION
Do not attempt a second start if fuel flow on initial start (prior to light-off) was above 700 PPH, or if maximum motoring speed was below 15% N2 or damage to engine could result.
You're only as good as your last departure.
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Hot Start On Engines, What Next?

Wed Apr 03, 2002 12:57 pm

The 600-800pph is straight from the maintenance manual. A higher than normal fuel flow at "fuel on" can indicate the possibility of a hot start. It is not an absolute that high initial FF will induce a hot start. In fact most starts go normal. But, I have never had a hot start (or actually an impending hot start) without the fuel flow being higher than normal at fuel on.

If you look strictly at EGT you are already behind the 8-ball. You have to look at all the parameters and make your conclusion based on what you see. A spiking EGT does not mean hot start, in fact the -7AH EGT goes like a bat out of hell to about 550c then settles out and rolls back. On hot days it may go to 600c. The limit is 650c.

You are correct that FF is a secondary engine indication, but is the first indication you will see that gives you a clue as to the health of the engine fuel system.
 
L-188
Posts: 29881
Joined: Wed Jul 07, 1999 11:27 am

RE: Hot Start On Engines, What Next?

Wed Apr 03, 2002 6:31 pm

This probably not in the book. But back in the day this used to be a really common occurance on a certian turboprop engine in cold weather say in the -20 -30 ambient range.

We called it a Garrett pre-heat. Usually the second attempt the oil would be fluid enough to get the engine to go.

I think the feds and the engine manufactures frown on this practice however.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Thu Apr 04, 2002 1:27 am

So do you abort the A310 start at 710 lbs per hr if everything else is normal. No; so that's not a hard limit, but it could be a secondary indication, as I've said.

My original objection was that fuel flow is the "first indication of a hot start."

By the above scenario, clearly it's not.

I've stated many times that secondary parameters (other than egt) should be in the start up scan.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Thu Apr 04, 2002 1:34 am

Also-

A spiking EGT should trigger an aborted start, which lends to the def of EGT as the primary, and in many cases, sole indicator of a hot start.

A rapidly rising fuel flow? Not necessarliy does the start have to be aborted; it must be compared to the other parameters.
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: Hot Start On Engines, What Next?

Thu Apr 04, 2002 7:41 am

Excessive fuel flow during initial fuel application, as spelled out by the engine makers and adopted by the airlines is the prime precurser of a hot start.

If, as you ask, do you abort the start when fuel flow goes to 710 PPH but everything else is normal? YES. Remember this is an instantaneous 710 PPH.

An analogy to that example would be, "On taxi out,do I stop extending the flaps because I heard ripping and crunching noises or should I try the next detent and see if the noise stops?

First off, how do you determine everything else is normal. This excessive fuel flow normally occurs before light-off.

The old saying, "an ounce of prevention is worth a pound of cure", rings true. Especially regarding hot starts.
You're only as good as your last departure.
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Hot Start On Engines, What Next?

Thu Apr 04, 2002 7:35 pm

FDXmech,

Thanks for the assist. I guess us freight dogs can teach others, or have operated enough crap to understand what the engine is trying to tell us.
 
JETPILOT
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

RE: Hot Start On Engines, What Next?

Mon Apr 08, 2002 4:26 am

Air2gxs.... fellow freight dog here to corroborate your info as correct.

One of my companies procedural callouts on start is "FUEL FLOW: NORMAL/HIGH".

If the fuel flow is "high"we abort the start and call maintenance. Let them crank the fucker over.

Its all determined by each individual company prescribed in the AOM.

First indication to you that the engine may hotstart in chronological order is as follows.

1. Engine fails to meet minimum N2.
2. Fuel Flow abnormal
3. Excesive EGT rise.

If number 2, or 3 indication is present you have an "impending hot start" which there is a procedure for in the abnormal section of your AOM.

If an engine actually hotstarts... meaning you exceeded your max start EGT limitation then you were sleeping. Because and engine wont hot start without some abnormal indication.

JET



 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 1:10 am

I still haven't seen fuel flow as a HARD limit in an FOM.

If everything else is normal, and fuel flow is high, (say 700 lbs/hr in the above ex), we start the engine. What "airlines" do is certainly not 100% standarized or compatible, as implied above.

All of the above verbage indicates higher fuel flows COULD be indicative of a hot start. That means it's subjective. As an engine approaches the need for an overhaul, startup fuel flows typically increase due to increased (greater than new spec) engine tolerances, dirty fuel nozzles, worn ignitors, etc.

For the above reasons, fuel flow can only be a secondary input to determining a hot start; not the primary.
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 9:42 am

I'm confused to what the actual debate is about, or are we talking semantics?

Let's clearly define the present point of contention.
You're only as good as your last departure.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 12:43 pm

I don't agree with the 4th post; for reasons I stated in the 5th and following posts and below:

1. A "possible indication" is NOT a limitation.
2. I've never seen a fuel flow (ie a specific value) as start limitation parameter.
3. For the above reasons, fuel flow can only be a secondary indication of a hot start.
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 1:39 pm

You run engines your way and I'll runthem my way, which by the way is the way our AOMs, MMs & training manuals tell us to run them.

 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 1:44 pm

...and the first time you turn a turbine into a slag pile you will come in and say "abnormally high fuel flow at light off really IS an indicator of a hot start."

High ff at light off should tell you to pay attention. No, it is not the ONLY sign, but it will be the first. Every mechanic I know uses that call out during light off.

Until you come up with a good reason NOT to monitor ff, can you at least admit its not a bad idea.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 1:49 pm

Have you not read a thing I've written????

Can you ref an FOM or anything else that specifies a STart Up, Fuel FLow LIMITATION?
 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 1:52 pm

Maintenance engine run check list for a CV-580 calls out for FF normal prior to the light off call. Only one I can think of off the top of my head, but I shall look if that is all you will believe. Why are you so opposed to the idea? Can you honestly say it is not the first warning you are going to have that it may be a hot start?
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 1:57 pm

Better yet...

Have ya started a jet (or any gas turbine) in the past 48hrs?

Not witnessed it, simulated it, read about it, or watched it...but actually risked turning it into a "pile of slag" yourself? If so, please describe - engine type, fuel flows, egts, OAT, location. What about your last hot start?
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:22 pm

What, exactly, is normal fuel flow for a Convair 580 on a standard day at Dallas Love with an 850 hr engine?

Otherwise reread what I wrote. Fuel flow is a secondary indication. If it is excessive, chances are another parameter is out of limits as well.
 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:24 pm

I frequently run Garrett TFE-731 and TPE-331 as well as some good ol' GE CJ 610's. Last start was about 9 am this morning (a 331.) I am also fully qualified on Alison 501's and C20's, PW 121's and PT-6's. I do alot of the OJT for run training at my airline and all of my trainees learn to monitor fuel flow, whether the checklist says to or not. I have never hot started an engine, although I have aborted starts that would have resulted in hot starts. I do probably as few as 3 runs to as many as 20 or more in an average work week. Believe me, I am qualified. A smart pilot who takes care of his aircraft will certainly get his mechanics opinion if ANY of the parameters are abnormal during start. I go out and monitor starts with pilots all the time if they think something isn't "quite right" and ultimately it is my call whether the engine is safe or not. A little more responsibility than pushing the start button don't ya think? Care to share your qualifications now?
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:26 pm

Don't need to...

But again, what is the max fuel flow limitation for any of those engines on start up?
 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:27 pm

You are making my argument for me. If fuel flow is abnormally high, the result COULD be a hot start. I never said that it was the primary indication, I said it was the FIRST indication. If you see high ff, you should sit forward and be prepared to abort. Can you give me one valid reason why this is such a bad idea? Or are you incapable of thinking outside of the box? "the checklist doesn't say to monitor ff, so it must not be important." That is a recipe for disaster.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:29 pm

You have current and contemporary experience with TPE 331s, PT6s or TFE 731s...and your first ref above was for a Convair 580?? That's rather strange...
 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:31 pm

You asked for a powerplant that reference fuel flow on the engine start checklist. The CV-580 is the only one I can think of off the top of my head.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:34 pm

FF can't be primary b/c there is NO defined LIMITATION; that's why it is defined as "Normal".

FF as a secondary, yes. Not primary; for the 5th time now.

If fuel flow is high, and other parameters are normal, start the engine: There was no limitation that was exceeded, and more importantly, if other parameters are normal, no damage.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:36 pm

OK -
So, AGAIN, what's a normal startup ff for a CV580 (STD day, Dallas LUV, 850 hrs)????
 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:37 pm

That is EXACTLY what I said you rube. I said it was the FIRST indication of an abnormal start. I did not say abort the start because of it. Geesh. You pilots, if you can't read it in your g-damned checklist then you can't possible understand it. Guys like you are what make me dream of the day when pilots are no longer part of the flight crew. Computers don't argue with something that makes sense.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 2:45 pm

Easy now. Rube is HARSH!

So, what is an abnormal fuel flow? If you can't define normal (for ANY of the powerplants you listed), how do you know what abnormal is? Sounds like your "FIRST indication" has zero meaning.

Where have you said that fuel flow can't be the primary indication? Or that it's a good secondary indication?
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 3:13 pm

"You run engines your way and I'll runthem my way, which by the way is the way our AOMs, MMs & training manuals tell us to run them."

I couldn't agree more. Since no Start up Fuel flow limitation is defined, fuel flow CANNOT be a primary decision criteria, it must be secondary.

Gee; I haven't seen it discussed on a checklist, so therefore I obviously can't understand it.


Yeah, right.

 
Metwrench
Posts: 715
Joined: Fri Aug 17, 2001 11:25 am

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 3:59 pm

My turbine engine experience for Maintenance run-up's:

RR Dart, fuel flow is extremely critical, a secondary "trimmer" is used during start to control engine temps and excelleration.

ALF 502, CT-7 & TPE-331, Engine Temp, RPM, and oil pressure rise are in the primary scan. Fuel flow is only observed when initiated then as a secondary scan if Temp or RPM is abnormal.

The "Garrett pre-heat" is a myth. The TPE-331 is a dry sump engine, oil is stored away from the engine. The engine capacity is 6 quarts, aprox. 3.5 are in the remote tank, 1 is in the cooler and external lines, 1 is in the prop, and 1/2 is left in the gearbox and filter. Further more, tubine oil viscosity changes little with temperature compared to recip oil.

The trick to starting a Garrett in cold weather is keeping the magnesium gearcase and the enclosed reduction gears warm. Then have either strong batteries or a GPU.

My opinion is that the leading cause of a "hot start" is slow acceleration. Therefore RPM is a critical perameter to monitor.
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 4:37 pm

Last engine run:

about 2 hours ago
N527UP
B747-200
JT9D-7Q
KSDF
Power run for trim due to throttle stagger gripe. All 4 engines.

OAT 54 F
EGT max start 505c (ours peak at about 375c - 400c)
FF on all 1,2, & 3 at fuel on was between 500pph and 700pph (within the MM range). # 4 was hovering around 750pph or so. It was a warmer start than the rest and ran hotter than the rest but well within operating limits.

Trim run came out OK.

Have never had a hot start because I pay attention to my instuments at start-up. I have had plenty of impending hot starts, that I aborted. In each case FF was abnormally high. I allowed the start to continue until I knew a hot start was going to happen and cut it off.

Maybe you mis-understand. Every high initial FF does not result in a hot start. Its just the 1st indication you get that tells you that you MAY have a hot start.
 
JETPILOT
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 5:44 pm

"Impending hot start" is on the FAA's list of things to do when certifying a crewmwmber.

If you dont catch a high fuel flow and make the call out... "Fuel flow high....Aborting.... Impending Hot Start".... and start reading the impending hot start abnormal checklist, you will leave the sim with a pink slip.

JET









 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 10:50 pm

Wrong.

The FAA doesn't write or define engine start procedures for ANY airline; the FAA only approves them. As a result, they leave the airlines to determine for themselves what a hot start is, and then approve subsequent procedures for it.

I challenge you to find ANY FAA reference that DEFINES a hot start or any kind of procedure, let alone a hot start/procedure by airline XYZ as a result of a high fuel flow. It doesn't exist.

 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 11:21 pm

"Maybe you mis-understand. Every high initial FF does not result in a hot start. Its just the 1st indication you get that tells you that you MAY have a hot start."

So is fire coming out of the tailpipe. This comment was the 4th post in the topic, and I disagreed in the 5th. Your description above is EXACTLY why FF is not a limitation, and therefore a primay indication, b/c there is way too much variation in what is normal. As stated, if normal is 700 lbs per hr, all parameters are normal except FF at 710, then that "1st indication" as you say, is of little value, b/c the start should not be aborted in this situation. FF is a secondary indication.
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: Hot Start On Engines, What Next?

Wed Apr 10, 2002 11:47 pm

There is no defined hard limititation on fuel flow because high FF in itself, does not constitute a parameter affecting the structural integrity of the powerplant (such as excessive temps or rotational speeds).

But there is an operating limit or guideline to initial FF to prevent hot starts.
------------------------------------------------------
Here's an example from MD11 (CF6-80) runup handbook:

Fuel Switch..........ON AT 17% N2 (MINIMUM)

Fuel Flow.............500-700 LB/HR (MAX)
------------------------------------------------------

Now, if your argument or point is, what parameter indicates a hot start. Well obviously it's EGT, but there is a way to avoid this unpleasantness. And that's to monitor FF at initial fuel switch opening.

Now you could choose to heed this helpfull data, which by the way didn't originate from myself or Air2gxs but actual testing & operational experience from the engine makers, engineering dept's, flight departments and M&E.

Or not.

In which case you must suffer from "the not invented here syndrome" or a low self esteem where you take as insult the fact you learned something you might not have known before, from someone else.

Or, you're egging us on. Smile
You're only as good as your last departure.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Thu Apr 11, 2002 3:38 am

Did I ask anyone to define what a hot start was? No way.

I didn't agree with the 4th post. FF is not a primary, or first indication of a hot start simply b/c there is too much variation in order to define a hard limit. The EGT start up limit, as a discrete value, is the primary startup indication. It should be backed by all other indications.

With other parameters normal, a high FF may just be a function of a more rapid start due to a range of conditions. So, it's not too effective as a primary criteria, is it?

I have made it very clear that, since start up fuel flows are given as an acceptable range and not a single limit, then this precludes FF from being a primary or first indication of a hot start. I have also asked for anyone to provide a specific value as a limit to startup FF. No one has. If all parameters are otherwise normal, and FF is high, the that is still a normal start.

FF as a startup parameter is only useful as a secondary indication. That's what I stated in the 5th post, and no one has proven otherwise. Why the diatribe on what "actual testing & operational experience from the engine makers, engineering dept's, flight departments and M&E"? NONE of those specifiy a specific value; therefore FF is NOT a primary indication.

I understand that...do you?
 
Guest

RE: Hot Start On Engines, What Next?

Thu Apr 11, 2002 3:47 am

If we would just accept the fact the each airline operates in it's own fashion, maybe we would stop having discussions with dozens of conflicting posts. For Essentialpowr you asked for a hard limit. Here is one. At my airline on our JT-8D equipped aircraft, the AOM limit on starting FF is 1100 pph. Our SOM is very clear that if inital fuel flow exceeds 1100 pph the start will be aborted. It does not say crosscheck EGT or any other engine instruments. If that conflicts with your experience, so be it.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Thu Apr 11, 2002 8:23 am

Bingo. A hard limit; so I would now concur that FF is a primary parameter for 727 pfe's airline. Thanks for the example.

The point is; until a discrete value for a parameter is defined, it cannot serve as a primary limit or indication for the engine start. For most airlines, FF is not a primary parameter.

Participants on this thread have stated a range of responses ranging from "Anything above normal" to "the FAA defines it", to my obvious disregard for AOMs, past operating experience, engine manufacturers, and the Statue of Liberty.

So maybe we should all read the our manuals, and understand exactly the defined limits are.

Cheers-
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: Hot Start On Engines, What Next?

Thu Apr 11, 2002 9:54 am

EP
You're exasperating, to say the least.
You're only as good as your last departure.
 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Hot Start On Engines, What Next?

Thu Apr 11, 2002 10:18 am

Okay, here ya go...from the manufacturers recommended operation procedures, NOT airline policy:

GE CJ610 Turbojet Operation Instructions

Normal Procedures: Engine Start

C. Turn starter and ignition ON and advance the power lever to IDLE at 10 percent RPM. Be prepared to discontinue the start and return the power lever to OFF should a hot start be imminent.

CAUTION: 1. FUEL FLOW IN EXCESS OF 350 LB/HR. WILL CAUSE HOT STARTS. DO NOT ALLOW STARTING FUEL FLOW TO EXCEED 350 LBS/HR BEFORE COMBUSTION OCCURS.

2. FUEL SYSTEM COMPONENT CHANGES MAY RESULT IN AIR BEING TRAPPED IN THE FUEL CONTROL. THIS CAN CAUSE HIGHER THAN NORMAL START FUEL FLOWS. BE ALERT TO THE POSSIBLITY OF HOT STARTS UNDER THESE CONDITIONS. IF NECESSARY, USE THE ALTERNATE STARTING TECHNIQUE AS DESCRIBED IN OPERATION ENGINEERING BULLETIN NO. 6

(emphasis is theirs, not added)

D. Monitor EGT. Initial EGT indication normally occurs withing 10 seconds from movement of the power lever to IDLE. The operator should be prepared to terminate the start in the event of an abnormally high indicated fuel flow, rapid EGT rise or overtemperature indication.




Hmmmm....a HARD limit that is not related to altitude or temperature. And, they put indicated fuel flow AHEAD of EGT as an indicator of an imminent hot start. Imagine that....

Next, from the Recommended Starting Procedures for the Alison 501-D13 as installed on the Convair 580:



(19) START BUTTON IN................ROTATION

(20) RPMS.................................2000

(21) FUEL FLOW..........................INDICATED (2000 MAX)

(22) 3 SEC AFTER FUEL FLOW.................LIGHT OFF




Hmmmm.... once again, a hard fuel flow limit as the FIRST indication of an abnormal start.

I could find others but you are not worth the time, especially since you won't even say what qualifies you to be such an expert on the subject. You may apologize at any time now...
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Hot Start On Engines, What Next?

Thu Apr 11, 2002 12:46 pm

So why couldn't you cite that parameter earlier? That's kind of "basic" isn't it? Quote it, and you've made your point as 727pfe did, and note, I accepted it at face value.

Instead, you cited the FF above "normal" on a CV580 was to be avoided, and that that suffices as a primary indication. "Normal" is not a limitation; that was my whole point. How do you teach that to a new FO or mech? It's going to vary from start to start, so if a company opts to define a FF limit, or an N1 limit, or oil pressure limit, vibes, etc, then those become primary. I'm sure somewhere out there XYZ airlines aborts a start on a Spey if the vibes exceed y.

I simply have stated that a hard limit must be defined to be a primary criteria. EGT is typically that parameter, and most airlines in the US don't set a startup FF limit, only a range, therefore making it SEcondary. I originally stated that I haven't seen FF specified as primary start parameter; it took 40 threads for you to cite a limitation you are supposedly familiar with.

Maybe now you've learned what a limitation is; then again, maybe this thread has been too technical for you...
 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Hot Start On Engines, What Next?

Thu Apr 11, 2002 3:26 pm

Um, you aren't worth talking to. I gave you the answer you wanted and you are still being nothing but an argumentative prick. You slashed everyone here who even slightly disagreed with you, and then when proven wrong you became even more juvenile than you were before. Unlike the people who responded to your rants, you contributed nothing to this conversation. If you honestly believe that fuel flow is NOT an important parameter to monitor during light off then you are an idiot. Nothing more. All the checklists and manuals in the world won't talk you out of that one. You are living proof that common sense cannot be taught and I am through arguing with you. To the rest of you, thank you for a delightful discussion.
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Hot Start On Engines, What Next?

Thu Apr 11, 2002 3:47 pm

Apathoid:

Ditto for me.

Who is online

Users browsing this forum: No registered users and 15 guests