UAL and Flaps 40

[Mach 80]

Back in the UAL 727 days I believe they locked out the Flaps 40 position so Flaps 40 couldn't be used. I think the same on the 737. Anyone know for certain why? I am guessing for noise or fuel burn or a larger airspeed margin to placard speeds or to reduce stress on the flaps for maint. reasons.

 

[Golden Falcon]

I would guess go-around performance limitations..

 

[FLYLOW22]

Noise restrictions... Phase 2 or 3 (one of em) mods that were put on the 727 included extending the exhaust portion of the engine nacelle and limiting the flaps to 30 so more power (noise) wasn't necessary to maintain the decent profile.

 

[pilotyip]

on the DC-9 they blocked out flaps 50. military still used them in the C-9B

 

[Sluggo_63]

Noise restrictions... Phase 2 or 3 (one of em) mods that were put on the 727 included extending the exhaust portion of the engine nacelle and limiting the flaps to 30 so more power (noise) wasn't necessary to maintain the decent profile.

This is why. I'm on the 727 at FedEx and Flaps 40 is blocked for the same reason.

 

[Chairman]

Flaps 40 were not locked out at UAL on the 737 other than by the airplane if you were going to fast I think 158kts you could move the flap handle but they would not move if you were to fast. If you were below the max extend speed they came out just fine although many pilots shy'ed away from ever using flaps 40

 

[FLYLOW22]

The one's I was writing about were safety locked and wired closed past 30 degrees.

 

[75 Driver]

Multiple answers: Flaps 40 definately locked out on some noise kits,

However long before that some airlines locked out flaps 40 due to some awfull landings and damage from said landings.

Remember some airlines really do not hire aviators, they hire people that will do what they are told and get along with others.

 

[Mach 80]

Yes, I was talking about before noise kits. I think UAL had them locked out on the 737-200's and/or 737-300's.

 

[bluechunks]

Yes, I was talking about before noise kits. I think UAL had them locked out on the 737-200's and/or 737-300's.

FWIW, UA did not lock out the 737-300/500.

 

[FLYLOW22]

FWIW, UA did not lock out the 737-300/500.

It was a hush kit to be used with JT-8D engines. 727/737-200/DC9.

 

[maru657]

United locked out the flap 40 position because some idiots racked all of the heat off on landing at about 50 feat and with flaps 40 the 727 will stop flying NOW! They actually bent some airplanes.

 

[b707guy]

Similar thing with Pratt-powered DC-8s, for stage 3 noise compliance. They are restricted to 35 degrees flaps for landing, except in an emergency. A small break-away tab blocks the flap handle from being moved beyond 35 to the original 50 degrees position. CFM-powered DC-8s are stage 3 without this restriction.

Our last stage 2 airplane (a -61) was restricted to 35 degrees max as well, but also had an alternate 'normal' landing flap setting of 25 degrees. Really funny that a 'normal' flap setting in that airplane is an 'emergency' flap setting in the rest. Especially in a plane that had non-modulated anti-skid and reverse thrust that produced more noise and forward thrust (or so it felt) than anything else... All for the sake of noise reduction.

 

[eaglesview]

United locked out the flap 40 position because some idiots racked all of the heat off on landing at about 50 feat and with flaps 40 the 727 will stop flying NOW! They actually bent some airplanes.

Where do you get this nonsense?? As for the 737's only the 200's where locked out of flaps 40. This was for noise certification.

 

[75 Driver]

The 727 lockout was definately done at UAL because of several aircraft damage incidents. Boeing and SAM along with FAA input took flight standards down this path a long time ago, if I remember correctly it was about 1986 this went down in the 72 fleet.

 

[tomgoodman]

Dropping like a brick

We could use 40 Flaps at DAL, but were told in 727 school that some carriers had prohibited that setting due to "sink rate" accidents in the early days of the airplane, when pilots were transitioning from straight-wing props. One example was a UAL crash at SLC in 1965. According to reports, the approach in that case was extremely unsafe: (over 2000 ft. high at the OM, sink rate 2300 FPM, hit short with 14.7 vertical Gs).

 

[SpauldingSmails]

Multiple answers: Flaps 40 definately locked out on some noise kits,

However long before that some airlines locked out flaps 40 due to some awfull landings and damage from said landings.

Remember some airlines really do not hire aviators, they hire people that will do what they are told and get along with others.

Perhaps it was both. Maybe flaps 40 was blocked to abate the noise of a B727 making a 14G impact. I'm sure that can't be very quiet.

 

[luckytohaveajob]

Flaps 40 keep the nose down. On low visibility approaches and with airplanes prone to tail striking flaps 40 shows good judgement.

 

[aa73]

IIRC, AA blocked out flaps 30 (safety wired) on the Raisbeck kit 727s. Flaps 25 was standard and we could only use 30 in an emergency. It's been too long so I may be wrong.