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727 Nose Wheel Brakes

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727 Nose Wheel Brakes

Old 20th Feb 2010, 07:46
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727 Nose Wheel Brakes

In an anarak moment a few weeks ago, I bought a Flight Engineers Training Manual for the 727 that I found in a second hand shop.

It has being very interesting reading so far. I am up to landing gear and it is now talking about the anti skid controllers for the NOSE WHEEL brakes.

I never knew that the 727 (or any aircraft for that matter) had nose wheel brakes.

Can you very knowlegable people please tell me more?
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Old 20th Feb 2010, 07:57
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Hi SOPS,

Many years ago I flew the 727-200 series airplanes for around 3,000 hours.

I seem to recall that the nose wheel brakes only operated when maximum braking was employed.
That is, they were very rarely utilized, to the extent that cannot recall them ever intentionally being used at all!

Great airplane, started in 1988 with the B727-238-15, and ended up operating the B727-269-17R, before moving on to the B747-200 series in 1994.

Great memories...

Cheers...FD...
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Old 20th Feb 2010, 08:04
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Hello,

Based on the repair manual for the NLG, brakes on the 727 NLG were an option - the NLG can be built with them or without them.

Brakes on NLGs are rare: fighter aircraft for unprepare surfaces/icy surfaces being one of the few places you tend to see them (SAAB, MiG).

NLG brakes can be normal brakes used to shorten stopping distances (either to squeeze the aircraft into a shorter runway than normal - maybe the 727 case) or small brakes to stop the wheel rotation prior to retraction (this is usually done by straps in the NLG bay - a lighter and cheaper and more reliable option).
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Old 20th Feb 2010, 08:24
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Hi SOPS,

By my best knowledge the Convair CV-990 Coronado was one of the few commercial planes equipped with a nose wheel braking system.. It was the contender of the B 707 and DC 8 in the 60'ties. Swissair was one of the few companies who bought them new. I remember the approach speeds were rather high .


Good Flying!


John
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Old 20th Feb 2010, 08:36
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Yeah NLG were an option. In our fleet we used to have more than ten aircraft equipped with NLG but I never heared of a replacement because they simply were not used. It's long ago but AFAIK the pedals had to be deployed to their maximum to activate them. (was there also a speed limit for them, don't remember?) There is very good reason for that. Everybody who has ever ridden a motorbike knows the forces up front during braking. So on the 727 nose gear strut the torque had to be limited not to overstress the strut. An option to get some better numbers on the performance charts like the option of rockets for engine failure on high elevation airports like La Paz.
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Old 20th Feb 2010, 09:13
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Not needed...

Yep, I flew the three-holer, as well....even sitting sideways.

The nose gear brakes, if equipped, were typically removed by most operators. Less weight, no maintenance, no need.

The 727 had great stopping capability. Never flew one with the nose wheel brakes....others have told me the thing really stops on a dime
when using the nose wheel brakes.

Fly safe,

PantLoad
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Old 20th Feb 2010, 09:21
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You guys are the best
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Old 20th Feb 2010, 09:55
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Ansett had the 727-200LR (long range) with nose wheel brakes. The penalty for them being u/s was 3000kg to the T/Off weight, so they must have had some effect on the accelerate/stop performance. Why remove them? Brakes are like engines, you can never have too many.
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Old 20th Feb 2010, 16:03
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Worked on a private -100 with nose gear brakes active in the late 90's. They kept them for short field performance at SKI resorts and small island strips. Belly's were all tanker fuel and they had in-flight oilers as the aircraft could fly longer than the oil supply would last in those old JT8's.
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Old 20th Feb 2010, 17:53
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In flight Oilers, how did they work ?
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Old 20th Feb 2010, 18:40
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Singapore had NWB on their 727-212 Adv. EAL also had NWB along on some of their 727-225Adv. aircraft. I believe both of these aircraft also had an AutoBrake function along with Auto Speedbrakes, ala B757/767.
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Old 20th Feb 2010, 21:24
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In flight Oilers

Been allmost 15 years but I remember engineer panel switches and a oil resevoir in the aft air stair area.

You perked my curiosity and I found a Trump -100 with oilers and a picture of the switches, far aft in the center of the panel. Worth a look anyways, this is one fine private jet.


Boeing 727-100 S/N: 20046 For Sale
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Old 20th Feb 2010, 21:45
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if my memory serves me correct from my 3000hrs on the B727-200, the nose gear brakes came efective after 70% brake pedal deflection, were hardly ever used, but remained installed due to the accel-stop performance advantages this gaves us.
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Old 20th Feb 2010, 22:01
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Flight detent in Post#2 states that he operated on Boeing 727-238-15.
Now, 38 is a Boeing customer number for Qantas and Qantas never bought or operated Boeing 727 aircraft.
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Old 21st Feb 2010, 05:31
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I've run across a couple 727 that still have the nose brakes in the last couple years. The rationale given was that the plane would have needed ballast anyway so why not carry something that might be useful some day v. bags of lead shot.

The oilers are popular with the VIP planes. Some of those planes are running around with the bellys stuffed with fuel, 80,000+ pounds at takeoff.
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Old 21st Feb 2010, 07:20
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Flight detent in Post#2 states that he operated on Boeing 727-238-15.
Now, 38 is a Boeing customer number for Qantas and Qantas never bought or operated Boeing 727 aircraft.
I suspect he typed that by accident, he meant 727-276.
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Old 22nd Feb 2010, 03:03
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Originally Posted by Romeo E.T.
if my memory serves me correct from my 3000hrs on the B727-200, the nose gear brakes came efective after 70% brake pedal deflection, were hardly ever used, but remained installed due to the accel-stop performance advantages this gaves us.
I believe that for nosewheel braking, 50% deflection of both brake pedals will activate nosewheel steering OR 75% deflection of any one brake pedal. If nosewheel brakes are installed, wheelwell fire sensing is installed in the nosegear bay. If I remember correctly, I believe that it is a single anti-skid unit for both nosewheels. Nosewheel braking is 'A' system operated unlike 'B' system main brakes.

There is a separate switch in the cockpit to deactivate the nosewheel brakes, however, nosewheel braking is also deactivated when the main gear anti-skid switch is turned off according to my manual, although nosewheel braking will still be applied upon gear retraction.

Brake wear indicators are checked with the park brake on. With the park brake set, the nosewheel brakes are not applied. Therefore to check the nosewheel brake wear indicators, you would release the park brake, have the ground interconnect open and at least one of the 'B' pumps on(electrically powered) with someone applying the brake pedals in the cockpit while you check the wear indicators on the nosewheel. Having the 'B' pump on with the ground interconnect open operates the 'A' hydraulic system.

The nosegear does have a single lockout debooster valve like each main gear brake has in order to deboost hydraulic pressure, provide leak protection and fluid quantity adjustment on the low pressure side of the valve as the brakes wear. Below that valve on the nosegear is the replenishing switch used to operate a solenoid to pressurize the nosebrakes for ground inspection and servicing(with 'A' system hydraulics available).

At least that is what my old notes say.

Last edited by JammedStab; 22nd Feb 2010 at 22:16.
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Old 22nd Feb 2010, 09:55
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The nosegear does have a single lockout debooster valve like each main gear brake has in order to deboost hydraulic pressure, provide leak protection and fluid quantity adjustment on the low pressure side of the valve as the brakes wear. Below that valve on the nosegear is the replenishing switch used to operate a solenoid to pressurize the nosebrakes for ground inspection and sevicing(with 'A' system hydraulics available).
Exactly.

Concerning activation of NLG. As a former FE I had to check the NLG with the replenishing switch and A pressurized in the morning. So someone in the cockpit had to push the pedals. ALL stated afterwards that they had to push it almost to the mechanical limit to activate the brakes.
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Old 22nd Feb 2010, 14:11
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In 15 years of running workshops doing wheels among other things I only ever saw one 727 NW brake, and I reckon from the state of it that had last been serviced 15 years previously!

The wheels themselves had drive keys as you might expect, and these keys aren't cheap. Many workshops never bother to look at them so when you overhaul the wheels and measure/NDT the keys per the CMM it's a fair bet that you'll reject some of the keys for wear or corrosion. When we did this not one customer wanted the keys replaced, they all opted to convert the wheel to an alternative P/N (basically just remove the keys).
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Old 23rd Feb 2010, 02:22
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Thanks "18-Wheeler"...

My mistake..you are quite right!

They were Australian Airlines airplanes.

Cheers...FD
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