PPRuNe Forums - Identify: 737-800 Engine probe / sensor?

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- - Identify: 737-800 Engine probe / sensor? (https://www.pprune.org/tech-log/560841-identify-737-800-engine-probe-sensor.html)

Mrglass

3rd May 2015 13:03

Identify: 737-800 Engine probe / sensor?

I can't find any reference to this protuberance in FCOM2.
Please identify its purpose (Boxed in red):
https://i.imgur.com/GY12OUn.jpg
It's on an SFP1-W if that helps.

barit1

3rd May 2015 13:52

It's on the t/r translating cowl, not associated with the engine proper. Maybe some shop people can help.:confused:

Big M

3rd May 2015 14:06

Not a probe. Just a lump of fibreglass/aluminium.

It's on the thrust reverser translating cowl. It is a ramp that pushes back a spring loaded section of leading edge flap for clearance when the T/R operates.

Try this picture

https://i1.ytimg.com/vi/d-wvNXU-PmA/hqdefault.jpg

STBYRUD

3rd May 2015 14:44

Aye, Boeing calls this the Krueger flap deflector:

Quote:

Purpose
The krueger flap deflector keeps separation between the
inboard leading edge (krueger) flap and the inboard thrust
reverser outer skin during these conditions:
* The inboard leading edge flap in the extend position
* Anytime the T/R is out of the stow position.
The fairing gives an aerodynamic surface for airflow around the
top of the thrust reverser.
Location
The krueger flap deflector is on the inboard T/R half of each
engine. The deflector is near the top of the T/R half. Bolts on the
inside of the translating sleeve hold the deflector in position.
You move the translating sleeve aft to get access to these bolts.
The fairing is just aft of the deflector. Bolts attach the fairing to
the T/R half structure.

The classics have it too, guess they didn't change the Kruegers much from the originals with its JT8D.

de facto

3rd May 2015 16:07

I am quite sure this is to protect the engine during reverser operation from the leading flaps possible droop.

Mrglass

5th May 2015 06:57

Thanks all for the informative responses. I believe we've cracked it.

I looked the other day and there is/are signs of rubbing/friction on a panel attached to the K.Flap; thus suggesting that the two do indeed rub up against one another when the T/R is deployed.

My understanding now is that this keeps a gap around the Nacelle so that air may flow freely outwards from the T/R grating when it is being used. If this gap wasn't there then ejected airflow from the deployed T/R may push forcefully against the nook formed by the engine cowl mount, engine cowl and extended K.Flap which may end up doing damage to the K.Flap.

Sound about right?

Found a good video showing the "guiding" properties of this device - clearly it creates a gap to stop unwanted excess friction of a drooping K.Flap - thus allowing free movement of the T/R aft.
https://www.youtube.com/watch?v=GsurWPENGY0

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