Quirkiest Quirk About Airliners?

JoeCanuck · Wed Feb 11, 2009 3:26 am

The gravel deflectors on some 732's were a bit of a quirk;

[Edited 2009-02-10 19:38:22]

ex52tech · Wed Feb 11, 2009 3:34 am

Quoting B777Neuss (Reply 97):
I also heard of a 727 with CFM engines. Do somebody have pictures or more information about it?

I have seen RR engines on a 727, and JT8-217s on a 727, but CFM.........I hope you don't mean CFM56 engines. I seriously doubt that, the weight alone would be problematic.

The JT8-217 installation is probably what you saw.

Stealthz · Wed Feb 11, 2009 12:06 pm

Quoting B777Neuss (Reply 97):
brake either in the right wheel and antiskid in the left or vice versa.

How does that work??

B777Neuss · Wed Feb 11, 2009 1:37 pm

Quoting StealthZ (Reply 102):
How does that work??

The system is/was mounted inside or behind the wheels. Both wheels were braked.

Quoting Ex52tech (Reply 101):
I have seen RR engines on a 727, and JT8-217s on a 727, but CFM.........I hope you don't mean CFM56 engines.

I never thought about weight issues, but someone told me that there were test flights with CFM engines. Like I sayed, I only heard about it.

BMI727 · Wed Feb 11, 2009 3:49 pm

Quoting B777Neuss (Reply 97):
I also heard of a 727 with CFM engines.

I don't know about CFMs, but all of the 5X 727-100s were re-engined with RR Tays.

Quoting Viscount724 (Reply 98):
The Lockheed L188 Electra and Navy P-3 based on the L188 seem to have a wider than usual cockpit

There was some old propliner (a DC-6 I think) that had the flight engineer sitting facing forward behind the pilots with his instruments on the back of the throttle quadrant.

Quoting JoeCanuck (Reply 100):
The gravel deflectors on some 732's were a bit of a quirk;

The gravel kit also includes those probes extending from the lower engine nacelle. They emit high pressure bleed air downwards to keep gravel and dust from being ingested into the engine.

B777Neuss · Wed Feb 11, 2009 5:08 pm

I had a look at the documentary again and should add that both wheels in the nosegear were braked with a disc brake which was only used after takeoff to avoid gyroscopic forces.

Mastropiero · Wed Feb 11, 2009 7:01 pm

Quoting B777Neuss (Reply 95):

Quoting Mastropiero (Reply 45):
Today, though, virtually no airliner has them.

Ok not today but "yesterday" Wink , the concorde had brakes in the nosewheel.

Not that it matters the slightest, but you quoted the wrong guy there.
smile

Filton · Wed Feb 11, 2009 7:09 pm

How about the Caravelle's triangular windows?

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Photo © Eduard Marmet

Anyone know of any technical reason for this - or was it just French design flair?

TripleDelta · Wed Feb 11, 2009 7:47 pm

Quoting Filton (Reply 107):
Anyone know of any technical reason for this - or was it just French design flair?

I've read that this was to increase downward visibility. The apex was at about eye-level, with the triangular shape giving an excellent field of view down (straight, left and right).

avt007 · Wed Feb 11, 2009 8:05 pm

Quoting AC320tech (Reply 99):
The Fokker F28 had this, and I have no clue why.

The F28 cockpit is quite wide, especially compared to a 737. The throttle arrangement gives the crew a nice ergonomic setup, with the throttles nice and close, instead of stretching to reach them.

Viscount724 · Thu Feb 12, 2009 4:29 am

Quoting Avt007 (Reply 109):
Quoting AC320tech (Reply 99):
The Fokker F28 had this, and I have no clue why.

The F28 cockpit is quite wide, especially compared to a 737. The throttle arrangement gives the crew a nice ergonomic setup, with the throttles nice and close, instead of stretching to reach them.

The L188 also appears to have separate landing gear levers for the captain and first officer (left hand photo in Reply 97). I'm not sure where the landing gear lever is on the P-3 in the right hand photo.

Max Q · Thu Feb 12, 2009 7:26 am

That's interesting Ex52 tech, I did not know you could literally separate the flap / slat handles on the MD-80, it sounds like it could be quite useful for maintenance purposes.

We were certainly never trained to do anything like that as Pilots. Off the subject I realise but I found the Md80 centre pedestal to be a mass of confusing levers, wheels and knobs after seven years on the 727.

Straightforward after a while but that flap / slat handle took a bit of technique to get the hang of as well..'

It would certainly be difficult and require a concerted effort to retract the slats inadvertently. A good thing when you see the size of the -80 wing !

greasespot · Thu Feb 12, 2009 4:12 pm

C-GXFA is the only B272-200 combi with a movable bulkhead....

It is still flying in this capacity for Firstair

GS

474218 · Thu Feb 12, 2009 5:11 pm

Quoting Max Q (Reply 111):
It would certainly be difficult and require a concerted effort to retract the slats inadvertently. A good thing when you see the size of the -80 wing !

The wing area of the MD-80 is larger than the 737-200/300 and only slightly smaller the 737-800/900.

MD-80 wing area 1209 sq ft.

737-300 wing area 989 sq ft.

737-900 wing area 1344 sq ft.

ImperialEagle · Fri Feb 13, 2009 1:58 am

Quoting Viscount724 (Reply 7):
how frequently reverse thrust was used in the air

Well, at DL, reverse-thrust on the -8's was a VERY common occurance.

Also, you are right about the IL-62's. I snapped a photo of one crossing Lejune Rd. just prior to touchdown at MIA with the buckets extended.

You should be familiar---------remember the "slipper" tanks that could be installed on Viscounts? I never saw too many of them so they always got my attention when I did.

[Edited 2009-02-12 18:20:58]

Viscount724 · Fri Feb 13, 2009 3:35 am

Quoting ImperialEagle (Reply 114):
You should be familiar---------remember the "slipper" tanks that could be installed on Viscounts? I never saw too many of them so they always got my attention when I did.

A few Viscounts with the slipper tanks.

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Photo © Chris Finney

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Photo © Mike Freer - Touchdown-aviation

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Photo © Steve Williams

dairbus · Fri Feb 13, 2009 4:35 am

The 727-200 had a small step folded up against the fuselage and secured by a lip on the bottom of the aft over-wing exit. When you opened the hatch inward, the step would fall by gravity and was held in a horizontal position by two straps. This was needed due to the shape of the wing which slopes down to the rear creating a 1-2 foot difference in height between the cabin floor and the top of the wing at that location. The step is visible in these photos as the trapezoidal shaped bump below the second over-wing exit.

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Photo © F. Camirand

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Photo © Ben Wang

You can just see the rear edge of the step in this picture.

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Photo © Benedikt Pressburger

ex52tech · Sat Feb 14, 2009 7:00 am

Quoting Max Q (Reply 111):
That's interesting Ex52 tech, I did not know you could literally separate the flap / slat handles on the MD-80, it sounds like it could be quite useful for maintenance purposes.

I was talking about the DC-10 being able to split the two levers, and was wondering if it was the same on the MD-80, because I could not recall...been a while.

Max Q · Sat Feb 14, 2009 8:53 am

Not sure about whether you could separate the flap / slat levers on the -80.

It was not something we ever did as Pilots.

HAWK21M · Sun Feb 15, 2009 10:00 am

Quoting Ex52tech (Reply 117):
I was talking about the DC-10 being able to split the two levers

whats prevents its misuse in flight?
regds
MEL.

ex52tech · Sun Feb 15, 2009 12:19 pm

Quoting HAWK21M (Reply 119):
whats prevents its misuse in flight?

There is a tab that flips up into to place and then screws into the back of the flap handle.
I can't find a good picture of it..........still looking.

LASoctoberB6 · Sun Feb 15, 2009 12:43 pm

Quoting 2H4 (Reply 9):
I nominate the JATO-equipped 727s flown by Mexicana:

Would someone explain what JATO-equipped means?

Quoting 2H4 (Reply 42):
If you touch the brakes while the aircraft is rolling backward, there's a good chance the nosewheel will come off the ground and the aircraft will come to rest on its tail.

I did that in Flight Sim a few years ago.. I thought something was wrong with the plane for wanting to sit back and relax.. But I guess it makes a lot of sense..

474218 · Sun Feb 15, 2009 3:01 pm

Quoting LASOctoberB6 (Reply 121):
Would someone explain what JATO-equipped means?

Jet Assisted Take Off (JATO). Actually the JATO bottles are small rockets which add extra thrust for takeoff.

HAWK21M · Mon Feb 16, 2009 6:34 am

Quoting Ex52tech (Reply 120):
There is a tab that flips up into to place and then screws into the back of the flap handle.

Interesting.
It would be great to view a picture.
regds
MEL.

stratoduck · Mon Feb 16, 2009 2:51 pm

according to my father, the main gears legs on the convair 880 could be extended at any speed as an emergency speed brake. once the aircraft slowed further, the nose gear could then be extended.

he recalls a flight to ORD in which the captain wanted to see if he could cross the outer marker at 340 knots and make the runway, and the above technique was used in the slowing of the aircraft. the aircraft was on speed and the engines were spooled up over the approach lights.

longhauler · Mon Feb 16, 2009 3:13 pm

Quoting Stratoduck (Reply 124):
the aircraft was on speed and the engines were spooled up over the approach lights.

And everything loose in the cabin was thrown against the cockpit door! Smile

Actually, the same could be done with the DC-7.

We used to do the same thing with the B737C with a gravel kit installed. The landing gear speed restriction from the gravel kit (180 knots) made some operations in busier airports pretty tricky. However, technically, the speed restriction was only on the nose gear. So we would use the emergency gear extension to extend the two mains, then use the normal extension to extend the nose gear.

BMI727 · Mon Feb 16, 2009 3:52 pm

Quoting Stratoduck (Reply 124):
the main gears legs on the convair 880 could be extended at any speed as an emergency speed brake. once the aircraft slowed further, the nose gear could then be extended

That Gulfstream that NASA uses to train shuttle pilots can do the same thing, as well as deploy the reversers in flight to simulate the glide down to earth.

AmericanB763ER · Tue Feb 17, 2009 12:15 am

I'm surprised that noone came up with this one yet ( although the Diesel 8 has been mentioned countless times in this thread ) - I'm talking about the high-lift devices called "slots" found on the DC-8 they are in the open-position and clearly visible on this great picture (the "valves" on the leading edge just inboard of the engines.)

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Photo © Geoff King

and I'm pretty sur no other airliner has a similiar system
Now if this isn't a quirk then nothing is.
Smile

JoeCanuck · Tue Feb 17, 2009 12:49 am

Quoting AmericanB763ER (Reply 127):

That is quirky...didn't it have slats?

avt007 · Tue Feb 17, 2009 3:15 am

The F28 main gear doors had a second door built into them, so that you could climb into the gearbay without dropping the doors. It was very convenient, and far more comfortable than trying to stand on the doors when they're opened.

AmericanB763ER · Tue Feb 17, 2009 8:41 am

Quoting JoeCanuck (Reply 128):
That is quirky...didn't it have slats?

No, DC-8 didn't have them - I think all of them (including the -70's) had the slots.

Marco

Max Q · Wed Feb 18, 2009 12:02 am

Here's one I just remembered from a long time ago.

The Saab 340 (then the SF340) had explosive bolts on the gear doors to open them in the event of hydraulic failure.

I have never heard of a civilian aircraft with explosive bolts before or since !

HAWK21M · Wed Feb 18, 2009 7:02 am

Quoting Max Q (Reply 131):
The Saab 340 (then the SF340) had explosive bolts on the gear doors to open them in the event of hydraulic failure.

Any details on the principle of operation of this "explosive" bolt.
regds
MEL.

Max Q · Wed Feb 18, 2009 9:02 am

I will see if I can dig up my ancient manuals on the Saab, cant guarantee anything !

HAWK21M · Wed Feb 18, 2009 4:42 pm

Quoting Max Q (Reply 133):

I will see if I can dig up my ancient manuals on the Saab, cant guarantee anything !

No pressure.The term was interesting though.On the B737NG there is a frangible fitting that breaks when contacted by a decapped tire & stops hydraulic flow to the gears.Is it somewhat similiar.
regds
MEL

BMI727 · Wed Feb 18, 2009 5:00 pm

Quoting AmericanB763ER (Reply 127):
although the Diesel 8 has been mentioned countless times in this thread

Did anyone mention the nozzles that moved backwards to keep the noise down yet?

474218 · Wed Feb 18, 2009 10:21 pm

Quoting HAWK21M (Reply 132):
Any details on the principle of operation of this "explosive" bolt.

The L-1011 Ram Air Turbine (RAT) is held in place by an "explosive" squib. When hydraulic power is lost the squib is fired and springs pull the RAT into the air stream.

Francoflier · Thu Feb 19, 2009 6:03 am

Quoting ImperialEagle (Reply 114):
Also, you are right about the IL-62's. I snapped a photo of one crossing Lejune Rd. just prior to touchdown at MIA with the buckets extended.

Just to add to the list, the Yak-40 also uses reverse thrust on the center engine before the flare.

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Quoting Viscount724 (Reply 110):
The L188 also appears to have separate landing gear levers for the captain and first officer (left hand photo in Reply 97). I'm not sure where the landing gear lever is on the P-3 in the right hand photo.

It reminds me of the Nord 262, which also had two sets of throttles and two gear levers. Even though the aircraft wasn't as wide as an Electra or F-28.

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Photo © Laurent Charpentier

Doors L3 and R3 on the 747 (overwing doors) cannot be opened on the ground when the wings are full of fuel, unless in an emergency, as they cannot be closed afterwards due to fuselage bending.

HAWK21M · Thu Feb 19, 2009 8:09 am

Quoting 474218 (Reply 136):
The L-1011 Ram Air Turbine (RAT) is held in place by an "explosive" squib. When hydraulic power is lost the squib is fired and springs pull the RAT into the air stream.

Interesting concept.
regds
MEL

UAL747 · Thu Feb 19, 2009 10:08 am

The Boeing 777 on take-off. If you watch the inboard ailerons, they are drooping with the flaps,. but as the engines throttle up and the plane gains speed, they go from droop, to almost sticking slightly above being flush with the rest of the wing, then they all of a sudden "kick-in" and droop back down with the flap settings.

Still to this day, no one has really given me any specific reason why this is so.

UAL

DH106 · Thu Feb 19, 2009 10:25 am

Quoting UAL747 (Reply 139):
The Boeing 777 on take-off. If you watch the inboard ailerons, they are drooping with the flaps,. but as the engines throttle up and the plane gains speed, they go from droop, to almost sticking slightly above being flush with the rest of the wing, then they all of a sudden "kick-in" and droop back down with the flap settings.

I read about this quite a while ago. I think the issue is that at low airspeed / high power settings (i.e. start of T/O run) the inner aileron when drooped, although not directly in the jet efflux can be prone to heating from the exhaust until the airspeed builds enough to 'mix' the air around it . So during taxi when T/O flap is set, the inner ailerons droop, but when T/O power is applied, they go up until a preset airspeed is achieved, then revert to drooped again for the actual rotation & T/O

UAL747 · Thu Feb 19, 2009 10:44 am

Actually, I know why they go downward later on because the hydraulics kick in sometime down the takeoff run, but why have them not already locked and down?

http://www.youtube.com/watch?v=Gity_aNvPHU

Also it is interesting to me that the 747 doesn't have flaps and their mod of extention from underneath the wings and retracting first the outer set, then the inner 2 sets. Also, when the thrust reverse is applied on the 747, the inner 2 sets retract.

Here's a climbout video i took on a flight from ORD-NRT

http://www.youtube.com/watch?v=hD7xj7lj_SI

and on landing

http://www.youtube.com/watch?v=e6ii2gRu9J4
UAL

[Edited 2009-02-19 02:46:15]

ex52tech · Thu Feb 19, 2009 7:44 pm

Quoting 474218 (Reply 136):
The L-1011 Ram Air Turbine (RAT) is held in place by an "explosive" squib. When hydraulic power is lost the squib is fired and springs pull the RAT into the air stream.

Seems a little 007ish. The DC-10 just used a plain old lever and cable set up that unlocked the up lock latch.

ex52tech · Thu Feb 19, 2009 7:49 pm

How about the air start bottle in the wheel well of some early 707's, used in the event one did not have an air start cart available.

474218 · Thu Feb 19, 2009 9:31 pm

Quoting Ex52tech (Reply 142):
Seems a little 007ish. The DC-10 just used a plain old lever and cable set up that unlocked the up lock latch.

and the DC-10 used chines in the stabilizer trim system, seems a little bicycleish?

avt007 · Fri Feb 20, 2009 12:12 am

Quoting 474218 (Reply 136):
The L-1011 Ram Air Turbine (RAT) is held in place by an "explosive" squib. When hydraulic power is lost the squib is fired and springs pull the RAT into the air stream.

Many CRJs have the same system. There are two types of ADG on CRJs, and the other has an uplock latch like a gear uplock.

Quoting UAL747 (Reply 141):
Actually, I know why they go downward later on because the hydraulics kick in sometime down the takeoff run, but why have them not already locked and down?

Sounds fishy to me. Hydraulic systems are either on or off in any particular phase of flight like takeoff.

474218 · Fri Feb 20, 2009 12:32 am

Quoting Avt007 (Reply 145):
Quoting UAL747 (Reply 141):
Actually, I know why they go downward later on because the hydraulics kick in sometime down the takeoff run, but why have them not already locked and down?

Sounds fishy to me. Hydraulic systems are either on or off in any particular phase of flight like takeoff.

Actually the hydraulic system is on anytime the engine is running, if the engine is turning the hydraulic pump is turning. There are switches that can be used to depressurize each individual system but they would only be used in an emergency.

UAL747 · Fri Feb 20, 2009 12:35 am

So then explain to me what is going on with the 777 then. I don't quite understand DH106's explanation.

UAL

474218 · Fri Feb 20, 2009 1:31 am

Quoting UAL747 (Reply 147):
So then explain to me what is going on with the 777 then. I don't quite understand DH106's explanation.

On the 777 the aileron droops when the flaps are lowered. However, it still functions as an aileron (for roll control). The reason the aileron is moving up and down is because the flight crew is putting roll inputs to the aileron. If they move the control wheel the aileron is going to move, simple as that.

UAL747 · Sat Feb 21, 2009 2:29 am

Quoting 474218 (Reply 148):
On the 777 the aileron droops when the flaps are lowered. However, it still functions as an aileron (for roll control). The reason the aileron is moving up and down is because the flight crew is putting roll inputs to the aileron. If they move the control wheel the aileron is going to move, simple as that.

No no....

Watch the video of the 777 taking off that I posted on here. The inboard ailerons do the exact same thing on both sides every time the aircraft takes off. They droop, then rise up, then go back down to droop position some time down the runway. It happens on both sides, and it's not pilot input.

UAL

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