737NG max start temp red line
Joined: Jun 2000
Posts: 4,507
Likes: 4
From: last time I looked I was still here.
I apoligise that I haven't the books to hand, so please read and correct me, but;....
I was always told that the start max temp magenta bug was variable. It depended on many ambient variables, e.g. OAT, altitude, density etc. For an Inflight Start 725c is specified.
I was always told that the start max temp magenta bug was variable. It depended on many ambient variables, e.g. OAT, altitude, density etc. For an Inflight Start 725c is specified.
Joined: Jan 2000
Posts: 860
Likes: 0
From: FL410
With the introduction of the NG Boeing removed the references from the Limitations section in the FCOM and used Red Line as a limit, the display telling you when you had an overtemp situation.
Prior versions of 737 had the temperature limitations mentioned in the FCOM (their engine instruments were a lot smaller and thus harder to read, their numeric display was easiest to read).
Engine limitations are still contained in the Limitations section of AFM though, even though Red Line limits were introduced. It is one of the few limitations not contained in FCOM for crew reference.
NG: 725/925/950
CL: 725/895/930
[Maximum temperatures for: start/continuous/takeoff]
Prior versions of 737 had the temperature limitations mentioned in the FCOM (their engine instruments were a lot smaller and thus harder to read, their numeric display was easiest to read).
Engine limitations are still contained in the Limitations section of AFM though, even though Red Line limits were introduced. It is one of the few limitations not contained in FCOM for crew reference.
NG: 725/925/950
CL: 725/895/930
[Maximum temperatures for: start/continuous/takeoff]
Joined: Feb 2005
Posts: 4,581
Likes: 0
From: flyover country USA
Good question, actually.
While I've been out of the circuit too long, in practice I recall there was a normal correlation between max start EGT for a given engine and residual EGT and OAT. (Not so much PA).
And I should think that a conscientious engineering organization could employ this relationship to create an alert level, objective being to flag an engine that is approaching a need for maintenance - despite no redline exceedance.
All of which might create another tug-of-war between ops and engineering.
While I've been out of the circuit too long, in practice I recall there was a normal correlation between max start EGT for a given engine and residual EGT and OAT. (Not so much PA).
And I should think that a conscientious engineering organization could employ this relationship to create an alert level, objective being to flag an engine that is approaching a need for maintenance - despite no redline exceedance.
All of which might create another tug-of-war between ops and engineering.
