Approach/Landing Climb Requirements and Fuel Jettison System

[AeroTech]

Hi,

FAR 25.1001 — Requires a fuel jettison system unless it can be shown that the airplane meets the climb requirements of FAR 25.119 and 25.121(d) at maximum takeoff weight, less the actual or computed weight of fuel necessary for a 15-minute flight comprising a takeoff, go-around, and landing at the airport of departure.

To comply with FAR 25.1001, the 747 and MD-11, for example, require a fuel jettison system. Some models, such as the 777 and some 767 airplanes have a fuel jettison system installed, but it is not required by FAR. Other models such as the DC-9, 717, 737, 757, and MD-80/90 do not require, or do not have, a fuel jettison system based on compliance with FAR Part 25.119 and 25.121(d).

I guess same statement goes with Airbus aircraft (if I am not mistaken).

Since DC-9, 717, 737, 757, and MD-80/90 are not fitted with fuel jettison system, does it mean that these aircraft will not suffer performance loss (payload loss) regarding FAR 25.119 and FAR 25.121(d)?

Feedback appreciated
Regards

[mutt]

Correct........... I have never seen a B747 limited by this restriction, but the MD11 can be at hot/high airports.

Mutt.

[Tmbstory]

I recall the Hercules L382 had a system that dumped at the rate of about 4000 lbs per minute. It was a consideration at certain critical times.

Tmb

[transducer]

Seem to remember something that stated that if the aircraft could land with a touchdown rate of 360fpm or less, above its max landing weight, and not cause any structural damage it did not require a fuel dumping system? This is an and/or inclusion to the approach/landing climb requirements. Been a while since I've been into this.

[Idle Thrust]

AeroTech wrote:

Since DC-9, 717, 737, 757, and MD-80/90 are not fitted with fuel jettison system

Although it is many years ago I put in nearly 6000 hours on the DC-9 and I can assure you that the DC-9-32's I flew definitely had fuel dump capability. Had much less time in the -15 series and cannot recall whether it had it or not.

[AeroTech]

Hi,

First I want to mention that the quote I posted is an extract from Boeing Aeromagazine, that’s why only Boeing aircraft were mentioned. Here the link:
AERO - Overweight Landing? Fuel Jettison? What To Consider (http://www.boeing.com/commercial/aeromagazine/articles/qtr_3_07/article_03_2.html)

Correct........... I have never seen a B747 limited by this restriction, but the MD11 can be at hot/high airports.

Mutt, are you saying that B747 is not limited (or will never be limited) by the approach and/or landing climb? If so why B747 is fitted with fuel jettison system? I guess B747 can land overweight???

I assume (I stand corrected) that A380 and A340 require fuel jettison system;
Some A330 are fitted with fuel jettison system but not required by the FAR; A320/A321/A319/A318 do not require fuel jettison system and do not have fuel jettison system.
I am wondering if A320 family will not suffer weight restrictions because of approach and landing climb requirements (FAR 25.119 and 25.121[d]).

Correct........... I have never seen a B747 limited by this restriction, but the MD11 can be at hot/high airports.

Mutt, I just want to confirm if the bolded part of your statement means that DC-9, 717, 737, 757, and MD-80/90 will not suffer weight restrictions during operations because of FAR Part 25.119 and 25.121(d).

Why the B777 and some B767 are fitted with fuel jettison system even tough these planes are not required by the FAR 25.119 and 25.121(d)? However DC-9, 717, 737, 757, and MD-80/90 are not required by the FAR 25.119 & 25.121 and not fitted with fuel jettison system.

Feedback appreciated
Regards

[mutt]

B747C has a MTOW of 377.000 kgs and MLW of 285.000 kgs (or thereabouts :))

It burns about 12.500 kgs per hour. So what happens if after takeoff you have a requirement to land ASAP, you have 3 options:

1: Land overweight
2: Burn off fuel (About 8.5 hours flight time)
3: Dump fuel

So although the regulation pertaining to fuel dumping may not be an issue, the ability to land ASAP might lead a manufacturer to install a fuel dump system, or an airline to purchase the option.

Mutt

[AeroTech]

Thank you for your posts.

I am wondering how long it takes to dump fuel from an aircraft (B747, MD11, A380, A340, B777) with MTOW to the required weight.

After engine failure at V1, can a MTOW B777 using MCT climbs above 5000/6000 ft (Boeing's general recommendation altitude whenever possible to jettison fuel)?

Feedback appreciated
Regards

[5LY]

All modern Boeing a/c can safely land at MTOW. If you just took off from it you can land on it. Some can dump fuel to get down to normal MLW. The B777300ER for example is only approach climb limited at sea level from above about 37 deg. c. It usually becomes an operational decision whether to keep the fuel and do the inspection, or dump it and waste the money. If you're on fire, different story. Get on the ground. You actually could safely dump with a fire, but why would you waste the time?

[syedo]

A340-600 dumps 1600kg/minute of fuel. so 380,000 - 265,000 = 115,000kg of fuel to be wasted. so 115,000 / 1600 = approx. 72 minutes..
if fire or dire emergency, no question asked, straight to overwt ldg. but if failure that require air turn back but without urgency, i suggest u call your company frequency and ak them whether to do a post overwt ldg check, or waste 115 tonnes of precious Jet A-1...:ok:

[AeroTech]

Hi,

Mutt and other members, thanks for the feedback.

FAR 25.1001 — Requires a fuel jettison system unless it can be shown that the airplane meets the climb requirements of FAR 25.119 and 25.121(d) at maximum takeoff weight, less the actual or computed weight of fuel necessary for a 15-minute flight comprising a takeoff, go-around, and landing at the airport of departure.

According to my understanding (narrow minded) of this regulation is that the installation of fuel jettison system is not related to overweight landing matter or land ASAP. The goal of installing fuel jettison system is to comply with the FAR 25.119 and 25.121(d).

To comply with FAR 25.1001, the 747 and MD-11, for example, require a fuel jettison system. Some models, such as the 777 and some 767 airplanes have a fuel jettison system installed, but it is not required by FAR. Other models such as the DC-9, 717, 737, 757, and MD-80/90 do not require, or do not have, a fuel jettison system based on compliance with FAR Part 25.119 and 25.121(d).

The Boeing guy who wrote the article and the quote above stated that: to comply with FAR 25.1001, the 747 and MD-11, for example, require a fuel jettison system.
To my understanding (again narrow minded), B 747 requires the fuel jettison system in order to comply with FAR 25.1001. I believe the fuel jettison system is a requirement for B747 certification and operation and not an option for operation.

It seems to me that Mutt has different opinion based on his posts:
” Correct........... I have never seen a B747 limited by this restriction, but the MD11 can be at hot/high airports.“

So although the regulation pertaining to fuel dumping may not be an issue, the ability to land ASAP might lead a manufacturer to install a fuel dump system, or an airline to purchase the option”.

5LY (post#10) said that the B777300ER is only approach climb limited at sea level from above about 37 deg c. According to Boeing guy quote's the jettison system is not required for the B777 but it is installed. I think the fuel jettison for B777 is an option because it improves aircraft performance as shown in this example.
So my question is: how come a B777-300ER is only approach limited at sea level and at 37 deg c and the Boeing 747 is not limited by FAR25.119 and 25.121(d)? (even at hot/high runway)

I am not arguing here, I am just trying to understand.

Your opinions are welcome.
Regards

[mutt]

[quote] 5LY (post#10) said that the B777300ER is only approach climb limited at sea level from above about 37 deg c[\quote]

Whilst this statement is correct, its out of context, the approach climb weights are as follows:

777-300ER MTOW 775.000 lbs

SL 36C = 785,600 lbs
SL 38C = 769,500 lbs

By comparing them to the takeoff weights we find:

SL 38 C Field Length Limit (11,000 ft/F15) 731,600 lbs
SL 38 C Climb Limit Weight = 763,100 lbs

If we look at 8,000 ft:

36 C = 544,600 (Approach Climb)
Field Length Limit 533,000 (about)
Climb Limit 535,000 (about)

So you can see that the takeoff weight won’t be limited by the approach climb, hence by legality a fuel jettison system isn’t required.

The MD11 has an AFM appendix about Takeoff Weight Limited by Fuel Jettison with a specific limitation code shown on takeoff calculations for this limitation, pure Boeing aircraft don’t have the same appendix nor limitation code.

Mutt