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Subject: MD 500 start question
 
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AirborneDaveUser is Offline
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Posts:68

12/12/2010 8:09 PM  
Just been reading about the MD500. In the MD500 POH during the start procedure it says you can go over the red line of 810°C for ten seconds with a momentary peak at 927°C not longer than 1 Second. Just curious when would you abort the start. I have heard of the MD500 going into the red on starts every now and then, is this bad for the engine? Also apart from following the POH, does anyone have any tips on avoiding hot starts? Merry Christmas
iMac__User is Offline
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Posts:154


12/13/2010 12:25 AM  
Posted By AirborneDave on 12/12/2010 8:09 PM
Just been reading about the MD500. In the MD500 POH during the start procedure it says you can go over the red line of 810°C for ten seconds with a momentary peak at 927°C not longer than 1 Second. Just curious when would you abort the start. I have heard of the MD500 going into the red on starts every now and then, is this bad for the engine? Also apart from following the POH, does anyone have any tips on avoiding hot starts? Merry Christmas
In general, maximum peaks are normally between 810C – 840C for about 2-3 seconds. However, if the temp runs rapidly pass 800C going to 900C roll to shut-off. Cooler starts maybe obtain by making adjustments at the fuel control. Having a well-maintained battery helps for cooler starts too.

Starts within the temperature limits are not additive and may be repeated without restriction; however, The repeated intentional use of transient temperature limits can result in reduced turbine life.

The following are probable causes of high temperatures during start:
 
Pilot over modulates fuel-flow during start-up
Attempting start with throttle (twist-grip) open
Premature starter release
Reduced battery capacity, weak battery
Insufficient time allowed for draining after an unsuccessful starting attempt
High residual TOT at start-up
Depreciated starter motor
Dirty compressor
Fuel nozzle valve stuck full open
Excessive compressor air leakage
Bleed value stuck closed
Fuel Control out of adjustment



Attachment: 250-C20 Maint.pdf


Regards,
Chris




ckellemsUser is Offline
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Posts:4

12/13/2010 1:58 PM  
Same engine, different aircraft... I don't let it get very far past 800 degrees. When it crosses 800, I'm looking at the rate that it's increasing. If it is slowed considerably, I'll continue the start and if not, I abort. I have probably never let it go past 830. This technique has kept me out of trouble for a couple thousand starts. By the way, great input on the causes of a hot start. Most of the ones I've seen have been due to a weak battery.
HeliGruppeUser is Offline
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Posts:1

02/23/2011 8:46 PM  
I found that using the old gauge, I can do multible starts say balancing a tail rotor unaided by an APU cause I can stay with the TOT, but The Diamond J TOT gauge will jump like a mad man so fast you dont know if its flashing to 799 or 1199 same zippy spike so I will use an APU. Also talked to a guy who sells a kit in Ca. for this problem.
Always check your Diamond J for OEC flashing so you dont get stuck with the over temp blame.
skipperUser is Offline
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Posts:155

04/27/2011 11:13 PM  
When turning on the battery switch You should be looking at the voltmeter. 24 volts or more is best. any less could contribute to a hotstart. Be ready to engage the starter with no delay after noting voltage. High ambient temperature will lead to hotter start temps. peak n2 rpm will help keep start cool , also note if not first start any residual tot or egt , don't introduce fuel even if you have achieved peak rpm until egt or tot is driven below 100c nominally.
little guyUser is Offline
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Posts:2

05/12/2011 1:10 PM  
Al the above responses are correct, but my first clue is the sound. You have this rapid increase in the speed of the aceleration, that's when I start to roll off the throttle.
mcflyiiUser is Offline
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Posts:1

09/09/2012 1:11 AM  
HeliGruppe Please contact me regarding your mention of the guy in Ca. who sells a kit for the the above mentioned TOT Gauge probelm mentioned above. THX
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