Tailwind limitations on engine start

[Whisky]

Hi

I was wondering if there are any tailwind limitations for starting our CFM56-7 engines on the B737-800.
There is nothing written in our manuals about max tailwind, there's not even any advisory information.

Surely there must be some kind of limit.
Any of you guys know more??

Thanx,
Whisky

[Chosun]

You have autostart? Failing that, you have an egt start limit? Presumably the manufacturers are confident that the start will be aborted if it goes pear-shaped, then you'll scratch your head and get towed round into wind for attempt number two.........
I've never heard of a tailwind starting limit, but the P & W -3A engines on the early classic jumbos needed about 15 knot headwind, minimum!!!!
:)

[Eckhard]

The Williams FJ-44s on a CitationJet have a limit of 10kts tailwind and 12kts crosswind for starting (and a start EGT limit of 1000 degrees C. Yes, that's 1000!). After all, they were designed to be started as they dropped from the belly of a B-52 at M0.8 and with an OAT of about -50.

[GlueBall]

There is one technique as a last resort: It's to deploy the reverser during initial rotation. :p

[Whisky]

Yes, we have an "abnormal start protection" provided by the EEC.
I guess that explains why there are no limits concerning tailwind on engine start etc.

I still would have expected at least some kind of advisory information or something like that.
Oh well, we'll see.

Thanks for the info guys.

Greetings,
Whisky

[MSLJ]

Hi

I got some information regarding engine start of the CFM56-5A3. This engine is fitted on the A320, so the informartion is taken from the A320 AMM (Aircraft Maintenance Manual).
Maximum tailwind is 10 knots. With tailwind from 5 - 10 knots maximum N1 is limited to 70%, 2 - 5 knots it is 85% N1 and 0 - 2 knots it is 90% N1.
I hope these informations can help you.

[projectman]

Boeing was specifically asked this question at a Synposium a couple of years ago and replied that there is no such tailwind limitation. They also recommended that reverser NOT be used in the process of starting the engines.

If required, due to strong tailwind, the raising of the start levers can be delayed beyond 25%N1 until correct N1 indication is acheived.