B737-400 noise

[Fly_146]

Hello,

Can anyone tell me what the common fit engine is/was on the B737-400?

What is the noise profile of the B737-400 engine?(lateral/flyover/approach)

Finally, the difference in noise rating between the 300 and 400 series B737.

Any help would be appreciated. Thanks in advance.

[747FOCAL]

Not sure exactly what you are asking???

the 737-400 has a CFM56 engine.

What weight are we talking for noise levels?

Difference in noise rating??? Not sure what you mean by that.

They both meet Chapter 4 if that is what you are asking. They have not yet been certified to Chapter 4, but they will make it. :)

[Fly_146]

747FOCAL,

Thanks for reply.

Basically - is the 737-400 any noisier than the 300 series? Also, where could I possibly lay my hands on documentation that would give reference to this? Also, what are the exact noise levels of the B734 in the three phases of measurement? Thanks.

[747FOCAL]

The 400 is quieter than the 300.

TO=85.7
SL=91.9
AP=100.1

:ok:

[TopBunk]

Fly146

I'm no expert by any means, but I would suggest that the only difference between the -300 and the -400 will be the rated thrust of the CFM56 engines. AFAIK the engine nacelles and exhaust areas are identical. This being the case, I would imagine the higher thrust rated engines will produce more noise IF greater thrust is used for a given phase of flight!

[Edited to add 747focals post crossed with mine, if he is correct then disregard all after .....]:O

[PaperTiger]

According to the FAA (http://www.aee.faa.gov/noise/AC_36-1H.htm) the -300 and -400 are within .1 db of each other with comparable engine fit. (No, I have no idea what a HWFAP is :confused: )

[xyz_pilot]

Real noise on a real dep will wepend a lot on wt and wx.

[Mark 1]

Certification EPNL is corrected to a standard sea level airfield, ISA+10, 70%RH and nil wind. The certification test measurements are corrected for the calculated heights etc. for the differences to the test day.

The take off measuring station is a fixed distance from the start of ground roll, so height can vary a lot depending on conditions.

For the approach condition the thrust must be set at what the manufacturers have calculated for those standard day conditions at MLW and nil wind with a flyover height of 394 ft.

[747FOCAL]

PaperTiger,

HWFAP = Hardwall forward Acoustic Panel. In other words they hardwalled about 5 inches of inlet right in front of the fan. Airbus does this as well on the A320. It helps smooth the airflow before the fan and reduces Buzzsaw noise, etc.

Not very many of the 737-300 and -400s have it as of yet. It is on the Next Gen 737 as standard equip.

:)

[PaperTiger]

Thanks F/O, HWFAP as an acronym seems to defeat Google :hmm: