For the aviation fans

[Long Wheel Base]

I had to do a fan lube and hub inspection this weekend on this CFM56-7B. It is fitted to a Boeing 737-800. The big fan you see when looking at the front is called the N1. As you can see once we remove the 24  blades that majority of the air is bypass air that just goes straight through the engine and out the back. About 80% of the thrust is created from this bypass air. These engines are called high bypass gas turbine engines. The air that goes through the engine that gets burnt with the fuel is mainly there to turn this big fan.

[Robbie Stewart]

Thanks for sharing, L.W.B. 

Very interesting indeed.

Tell me, that protrusion in the last pic, upper left, is that a fuel injector?

 

You guys must be pedantic about not losing any parts when disassembling an engine. I watched an episode on Airport Dubai a while back, and there was an insert where some technical blokes had to do something to one of those GE90's on a 777. Anyway, the angle was near impossible, and the poor guy ended up dropping the screw into the depths of the engine. It took some patience, a good measure of luck, and another senior technical guru to also drop the screw a second time, even deeper into the bowels of the jet, before finally getting it out in the nick of time, saving a engine change, and Emirates some embarrassment and huge cost overruns due to plane rescheduling. 

You guys work in an insane environment. Respect.

[SwissVan]

Thanks for sharing, L.W.B.

 

Very interesting indeed.

 

Tell me, that protrusion in the last pic, upper left, is that a fuel injector?

 

You guys must be pedantic about not losing any parts when disassembling an engine. I watched an episode on Airport Dubai a while back, and there was an insert where some technical blokes had to do something to one of those GE90's on a 777. Anyway, the angle was near impossible, and the poor guy ended up dropping the screw into the depths of the engine. It took some patience, a good measure of luck, and another senior technical guru to also drop the screw a second time, even deeper into the bowels of the jet, before finally getting it out in the nick of time, saving a engine change, and Emirates some embarrassment and huge cost overruns due to plane rescheduling.

 

You guys work in an insane environment. Respect.

I’d hazard a guess and say it’s an air pressure or temp sensor for the engine control system...

 

Over the years I spent working on aircraft I’ve found some pretty interesting items that got lost.... most of the time not in the guts of an engine.... a few on top or at the bottom of the engine.... LOL

 

When I worked on planes we had to buy our own general tools and each engineer would mark his tools to try prevent mixups or theft.... however if you left one somewhere you shouldn’t ( it happens) it could come back and bite you.

 

Big culprits were the assistants, unqualified guys who help out with the more menial tasks.... they used to use the engineers tools whom they were working with.

 

Overtime safety regulations have increased focus on this issues and tool control has improved..... somewhat ????

Edited February 4, 2019 by SwissVan

[kosmonooit]

from what i understand the evolution of high bypass engines has been driven by efficiency, meaning its much more efficient to have a gas turbine turning a big ducted fan, previously most of the air sucked in went into the compressor, injected with fuel and set alight.

 

Also the evolution of materials for this composite fan blades has been enabling.

 

The issue has been the size of the engines, they have had to move them, forward and up so they can clear the ground, like in the latest 737 Max

 

The tendency is toward bigger (increase bypasss)  engines - the latest is the hooj GE9x they are getting ready for the 777x -seen here on a 747 test bed

 

 

 

 

 

 

 

[kosmonooit]

Compare the 737 Max to the ole -100  fluffy

 

 

 

 

Still in service with Air Zim apparently

[kosmonooit]

Edited February 4, 2019 by kosmonooit

[SwissVan]

from what i understand the evolution of high bypass engines has been driven by efficiency, meaning its much more efficient to have a gas turbine turning a big ducted fan, previously most of the air sucked in went into the compressor, injected with fuel and set alight.

 

Also the evolution of materials for this composite fan blades has been enabling.

 

The issue has been the size of the engines, they have had to move them, forward and up so they can clear the ground, like in the latest 737 Max

 

The tendency is toward bigger (increase bypasss) engines - the latest is the hooj GE9x they are getting ready for the 777x -seen here on a 747 test bed

 

 

 

 

 

 

 

For those who don’t like flying in aircraft with propellers....

Just a big propeller with a cowling wrapped around it

 

????

[Lotus]

For those who don’t like flying in aircraft with propellers....

Just a big propeller with a cowling wrapped around it

 

 

That's interesting! Like the propulsion on the RC "jet" aircraft where the props are enclosed?

[Robbie Stewart]

Compare the 737 Max to the ole -100 fluffy

 

 

 

 

Still in service with Air Zim apparently

First flight in a airliner was on one of these boeings. I remember my visit to the cockpit, and the captain letting me push a button on the autopilot console which started our descent into Durban. Early 80's sometime.

[kosmonooit]

Just for some additional perspective

I see there are still quite a few -100's in service elsewhere in the world, one unique feature it has (optional) is a protrusion in the front of the engine intake that blows dust away on landing.

 

Those reverse thrust umbrellas are always a good laugh, but they have stood the test of time.

Edited February 4, 2019 by kosmonooit

[Long Wheel Base]

Thanks for sharing, L.W.B. 

 

Very interesting indeed.

 

Tell me, that protrusion in the last pic, upper left, is that a fuel injector?

 

You guys must be pedantic about not losing any parts when disassembling an engine. I watched an episode on Airport Dubai a while back, and there was an insert where some technical blokes had to do something to one of those GE90's on a 777. Anyway, the angle was near impossible, and the poor guy ended up dropping the screw into the depths of the engine. It took some patience, a good measure of luck, and another senior technical guru to also drop the screw a second time, even deeper into the bowels of the jet, before finally getting it out in the nick of time, saving a engine change, and Emirates some embarrassment and huge cost overruns due to plane rescheduling. 

 

You guys work in an insane environment. Respect.

As swissvan said, its a sensor. The fuel injectors sit further back inside the "hot section" of the engine. A course for an engine like this is a week long and we spend probably a day at least just learning about all the sensors and how they work and effect the engine performance so I won't bore you with exactly how this one works but in plain and simple terms it is an airflow sensor used for EPR(engine pressure ratio).

We have had situations where bolts/nuts have been dropped inside the engine itself. If the engine is on wing then you WILL find it before starting that engine. There are boroscope ports all over the engine and we put a 6mm(mostly, some need a 4mm) probe inside and look for it. 

[Long Wheel Base]

from what i understand the evolution of high bypass engines has been driven by efficiency, meaning its much more efficient to have a gas turbine turning a big ducted fan, previously most of the air sucked in went into the compressor, injected with fuel and set alight.

 

Also the evolution of materials for this composite fan blades has been enabling.

 

The issue has been the size of the engines, they have had to move them, forward and up so they can clear the ground, like in the latest 737 Max

 

The tendency is toward bigger (increase bypasss)  engines - the latest is the hooj GE9x they are getting ready for the 777x -seen here on a 747 test bed

 

 

 

 

 

 

 

It is A LOT more effective. High bypass is the way to go. They also a lot quieter. The N1 fan blades of some of these newer engines are now a carbon composite. It is crazy how light they are. Another advantage is when you have a birdstrike, in most situations(smaller birds that are commonly sucked in) the blades are designed to deform to absorb the impact and after about 3 rotations it is back to its original shape. On the "older" blades that are metal the blade just bends and we have to replace them.

[Robbie Stewart]

As swissvan said, its a sensor. The fuel injectors sit further back inside the "hot section" of the engine. A course for an engine like this is a week long and we spend probably a day at least just learning about all the sensors and how they work and effect the engine performance so I won't bore you with exactly how this one works but in plain and simple terms it is an airflow sensor used for EPR(engine pressure ratio).

We have had situations where bolts/nuts have been dropped inside the engine itself. If the engine is on wing then you WILL find it before starting that engine. There are boroscope ports all over the engine and we put a 6mm(mostly, some need a 4mm) probe inside and look for it. 

 

No need to worry. Above in red is not likely to happen when chatting about aircraft and anything related. I am a nutter about aircraft, and sadly missed out on being a part of this industry. Still, I appreciate any sharing.

 

I can only imagine the stress involved in looking for a missing bolt or nut in a plane engine, especially if that plane is scheduled to shortly depart.

 

I have a cousin who I have not seen in about 30 years. She is married to a bloke who was part of SAA Technical back in the day. He was OCD to the max, and we always joked you had to be OCD to work in his job.

[Robbie Stewart]

Just for some additional perspective

I see there are still quite a few -100's in service elsewhere in the world, one unique feature it has (optional) is a protrusion in the front of the engine intake that blows dust away on landing.

 

Those reverse thrust umbrellas are always a good laugh, but they have stood the test of time.

 

 

Awesome perspective. I would love to be in the vicinity to hear one of those GE9X beasts roar to life. It must be simply earth shattering.

[kosmonooit]

As LWB, says one advantage to the higher bypass ration engines is that they are much quieter, the chevrons on the tail end of the nacelle that you find on some engines like on the Dreamliner and 747-800, 737 Max make it even quieter 

 

These jet engines are  a constantly evolving technology and materials science plays big part, even deeper in the engine, including the hot section, new materials and composites are being used (like composite ceramics) - even just a few % in fuel savings means a lot to airlines.

[Lotus]

 

We have had situations where bolts/nuts have been dropped inside the engine itself. If the engine is on wing then you WILL find it before starting that engine. There are boroscope ports all over the engine and we put a 6mm(mostly, some need a 4mm) probe inside and look for it. 

 

It's certain when I work on my car engine that I'll drop at least one bolt and never see it again. And when I'm done there will be bolts left over that have nowhere to go.