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Jetranger Ii Vs Jetranger Iii


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Hi folks,

 

Trying to remember the differences between a JRII and a JRIII, as far as limitations go. TOT max. cont in a JRII is 737 vs. 738 in a JRIII I believe. There are a couple other small differences as well aren't there?

 

Bigger tailrotor in the JRIII, also a bigger engine? What is that, a C20B vs a C20J?

 

Fire away, thanks for your help.

 

Happy New Year to all.

 

Coastal

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From what I remember... ( and this crowd will correct my mistakes :D )

 

Max TOT is different. 795 vs 810 (??)

TR diameter can be different ( 65" vs 62").

TR drive shaft is probably different, Larger TR needs the segmented shaft (??)

TRGB output shaft is different, (tapered)

Engine is 250C20B or J vs 250 C20

 

Not much In-Flight differences below 8,000, much better TR authority and TOT above that altitude.

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TOT is 795 and 810.

 

Segmented shaft was introduced around serial number 1250, so it was still a Jetranger II.

 

Oil cooler blower is bigger on a III, the oil lines are a larger diameter.

 

The oil cooler deck is composite on a III, aluminum on a II. (The composite has a drain pan under the cooler, the aluminum one is open into the heater deck. You need to know that when washing the oil cooler blower.)

 

T/R gearbox is a different number on a III with a much thicker output shaft.

 

Different servo mounts between the two.

 

The III's have 'slam doors'. DON'T slam them.

 

Location of fresh air vents is different on nose.

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Alright, so as far as limitations go, is the only difference between the two reflected in TOT?

 

JRII: Max Cont: 737; Max T/O: 795

JRIII: Max Cont: 738; Max T/O: 810

 

I thought there was some slight variation in max N1 as well, 105% vs 106% max.

 

Thanks again.

 

Coastal

 

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TOT is 795 and 810.

 

Segmented shaft was introduced around serial number 1250, so it was still a Jetranger II.

 

Oil cooler blower is bigger on a III, the oil lines are a larger diameter.

 

The oil cooler deck is composite on a III, aluminum on a II. (The composite has a drain pan under the cooler, the aluminum one is open into the heater deck. You need to know that when washing the oil cooler blower.)

 

T/R gearbox is a different number on a III with a much thicker output shaft.

 

Different servo mounts between the two.

 

The III's have 'slam doors'. DON'T slam them.

 

Location of fresh air vents is different on nose.

 

There were rotorhead and freewheel changes too but I can't recall the serial number break.....may have actually been in later B2's like the segmented shaft and blower. Of course all B2 post SI-112 have some of this crap too so quite a bit of overlap between the B2 and B3 mechanically.

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There were rotorhead and freewheel changes too but I can't recall the serial number break.....may have actually been in later B2's like the segmented shaft and blower. Of course all B2 post SI-112 have some of this crap too so quite a bit of overlap between the B2 and B3 mechanically.

 

 

and for reading pleasure, "INFORMATION LETTER 206-04-89" which uses SI-112 for the Gross Internal Increase STC.

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