Idle N1,EGT,N2 Indications
 

Hi all,

I'm sitting here with some questions about B737-400 and 800.

I've now been roaming threw all Boeing books and cant find anything about IDLE Indications on Ground.

I've got this thumb rule about an engine being stabile at
"2-4-6" or "20-N1, 400-EGT, 60-N2"

Also flying the 800 when the small red line disapere after ENG start the engine is considered stabile.

Can anyone plz let me know where the acurate numbers are writen, since these test paper answers differ the answers for N1 by 18,20,22,24 for both B737-400 and 800.

The rule of thumb I learnt was 2-4-6-3

N1=22
EGT=450
N2=60
FF=.3

These numbers are for the Classics and are approximate, except perhaps for N1 which should be 22% (cf flight idle at approx 32).

the EGT will vary considerably depending upon ambient conditions & engine condition, hence you probably wont find the "accurate numbers" written anywhere. NB the NG EGT may be below 400

The "small red line" on the NGs is the EGT limit for start, it also varies with ambient conditions. When it disappears the big red line is applicable.

S&L

The B737-3/4/500 AMM 71-00-00 p280H states:
Let the engine become stable at low idle RPM and make a check for these "approximate" indications:
N1- approx 21.5%
N2- approx 60%
FF- 550-950 PPH or 250-430KGPH
EGT- 450.C-650.C

ENG overspeed is dealt with else where in the same chapter aswell as overtemperature.

The most accurate way of finding out your answer is through the maintenance manual. The manual has rpm and egt for different altitudes, temperature and baro pressure for trim runs.