Refueling Control Panel

This is the place where control for refueling process took place. Located at the forward edge of right hand lower surfaces. Amount of fuel required base on the flight plan will be routed to certain tanks by controlling the switch of each tank. What unique about BBJ is that, there is additional control for auxiliary fuel tank which is located in forward and aft cargo compartment.

Normally the wing tank will be filled up first followed by the center tank, any extra fuel required then will be routed to the auxilliary tank. Depend on the density of the fuel for that day (fuel density varies mainly due to temperature) the maximum quantity for each wing tank is 3800 kg (4800 liters) and center tank 12750 kg (16200 liters). For auxilliary tank, on BBJ that i work on it has 1 auxiliary tank at the forward cargo and 3 tank in the aft cargo, each can be filled up to 1500 kg (1900 liters) and 2900 kg (3600 liters) respectively.

In each tank there is an instrument that will measure the capacitance of the fuel and from that through fuel processing unit will convert it to kilogram. Weight of the fuel is more relevant for aircraft as it will be added to total weight of an aircraft to determine take off thrust setting for engine for that particular flight.

My New Blogs

From now on i will on ly post technical information in this blog, posting about my experience, fun and joyful article will be in the following blog.

http://dutytravel.blogspot.com

For those who had asked questions to me in a past, i post the questions and answers in this blog.

http://askengineerhelmi.blogspot.com

Enjoy..

Auxilliary Fuel Tank

BBJ (Boeing Business Jet) can travel longer range compared to conventional 737 due to this extra fuel tank added in its cargo hold.

Depend on certain configuration per customer specific need, this extra tank can be placed at aft area of the forward cargo or forward area of aft cargo hold. This is to ensure center of gravity of the aircraft remain close to the center of the aircraft.

Each tank can hold around 1800 liters of fuel which if converted to kilograms will be around 1500 kg except the master tank which will have much higher capacity.

All fuel from auxiliary tank will be routed to the center tank of the aircraft before goes to the engines. What unique about this system is, fuel from auxiliary tank is "pump" to center tank using differential pressure from the cabin which will start once fuel in center tank dropped to certain level.

During initial refueling before the flight, the fuel will be added to the wing & center tank fuel first, extra fuel required for the flight then will be filled up in this auxiliary tank.

It's hard to see how this aux tank looks like, i found this extra tank kept in the store, it has been removed form one of the BBJ due extra cargo space required for the baggage. if you need extra range for the distance, cargo space has to be sacrifice for the fuel tank...

CFM Engine Using BioFuel

BBJ is using CFM56-27 engine for it propulsion system, what i want to highlight here is in June 2007, the engine manufacturer CFM International has successfully carried out an initial test of a CFM56-7B engine using an ester-type biofuel at Snecma’s Villaroche facility near Paris.

CFM56 engines are produced by CFM International (CFM), a 50/50 joint company of Snecma (SAFRAN Group) and General Electric Company.

The biofuel used for this test is 30 % vegetable oil methyl ester blended with 70 % conventional Jet-A1 fuel. This test was designed to check the operation of a jet engine using a fuel made from biomass, without making any technical changes to the engine. With this type of biofuel, the target is a net reduction of 20 percent in carbon dioxide (CO2) emissions compared with current fuels.

CFM is running engine tests to develop solutions based on mixtures of jet fuel and second-generation biofuels. For instance, it is currently focusing on the evaluation of alternative fuels made using biomass (offering properties closer to those of jet fuel), which also offer better environmental performance.

For alternative fuels to be used in the aviation industry, there are a number of major technology challenges that must be met, including energy density, thermal stability (avoiding coking at high temperature), use at very low temperatures (freezing) or high temperatures, lubricating effect with materials used, and the availability of mass production facilities worldwide.

Even though it is only 30% "vegetable oil" as a start, it is a major step toward greener emission from aviation industry.

Aircraft Maintenance Engineer - Unknown facts by non aviator

When we are in the airport, a lot of times we can see the pilots and cabin crew walking by us and begin admiring their glamorous career on board the aircraft, but do we know who is the one responsible for the maintenance aspect of the aircraft that they working on? That person is Licensed Aircraft Maintenance Engineers, he is the one responsible to make sure that an aircraft is save to fly, to carry passengers or cargo's from one point to another point.

All aircraft maintenance engineer must have a license from local aviation authority to exercise his privilege which is to certify that an aircraft the he had inspected is fit for release to service.

How to become an engineer? Well, first of all you must have an interest on the aircraft itself because if you don’t like it or feel that there is nothing special about an aircraft then it will be more likely that you will not pass the exam or test to get the license. Practical knowledge is essential as it will make it easier to answer the questions in the license exam.

There is a lot of aircraft maintenance engineer training school that offering course to become an aircraft maintenance engineer, in fact Malaysia Airlines as well as Air Asia does have their own training department to recruit new aircraft maintenance engineers.

Training normally will took around 4 to 5 years, Malaysia Airlines for instance will provide an allowances to the trainees that join their training program however they will be bonded for few years once the trainee succeed his training program and established as licensed aircraft maintenance engineer.

Aircraft maintenance engineer can be divided into few categories, it can be Line Aircraft Maintenance Engineer or Base Aircraft Maintenance Engineer, apart from that they furthermore can be divided into trades that they are rated which is either Airframe Maintenance Engineers, Engines Maintenance Engineer, Avionics, Electrical or Radio. Aircraft Maintenance Engineer can be multiple trade as well. Normally Airframe Engineer will hold Engine license. Electrical, Avionic and Radio Aircraft maintenance engineer normally has all 3 rating with them.

Line Aircraft Maintenance Engineer normally attached in front line of service as they handle the aircraft for departure or in transit in the airport terminal while Base Aircraft Maintenance Engineer is the person who will inspect an aircraft when it is in the hangar for major inspection.

For trade classification, Airframe Maintenance Engineer will responsible to the defect or inspection related to the airframe part of an aircraft which is the fuselage, flight control, hydraulic, air conditioning system, including the passenger seats and so on. Engine Maintenance Engineer for the engine and auxiliary power unit of an aircraft, same goes for other trade. However only Airframe and Engine rated aircraft maintenance engineer has the privilege to release an aircraft back to service (flight) as a whole, for instance if there is a defect of electrical component, electrical maintenance engineer will rectify it however he will only certifying whatever job he did, before the aircraft can fly, the airframe and engine engineer then inspect the aircraft base on the inspection procedure laid down by the manufacturer and then certify that the aircraft is safe to fly. Certification will be in a form of signature plus the approval number from authority or company, stamped or be wrote down on the aircraft legal document which will be on board. One copy of the signed document will be leave on the ground before the door of the aircraft close for departure.

Once he put his signature in that document, he is responsible for the safety of the aircraft, the passengers, the cargo as well as the crews. Anything happen to the aircraft, licensed maintenance engineer that released the aircraft for flight will be the one that will be called by the aviation authority for an investigation. Base on this information I’m sure know the readers will realize who has the biggest responsibility once the aircraft lift off from the ground.

Dr Marten - Aircraft Maintenance Engineers official shoes

I just bought myself a pair of low cut black Dr Marten shoes for myself when i was in London. It cost me 50 pounds. Dr Marten shoes become common to aircraft maintenance engineers (AME) due to it oil, fat, acid and alkali resistance. Beside that it bouncing sole is really make it very comfortable to wear.

This is my third Dr Mart actually however to my surprised, it is no more made in England, instead it is now made in Thailand, huh.. globalisation... anyway seems the finishing and quality almost the same, the only different now for sure Dr Mart company profit will soar.

Dessert For VIPs

Most of the food served onboard the aircraft is way above standard of commercial airlines, of course if compare with economy class. Even on some airline that i flew on first class, the food served not as marvelous as what been served onboard our BBJ.

This chocolate cake by Paind'or was uploaded onboard in Lebanon, surprised me that in Lebanon this luxury cake is available there.

Below is cheese cake from Riyadh itself, is it yummy?

Refueling the aircraft.

How many of us really knows how refueling of an aircraft is done and where is the fuel tank for an aircraft is located? Probably not many know as well what type of fuel aircraft used. Aircraft fuel which is basically a highest grade kerosene will be pumped up by the fuel truck using the hose connected to the refueling panel.



At the fueling panel which is normally on right hand side of the aircraft wing's on majority of the aircraft, there is a control switches that open and close shut-off valve for each tank that fuel have to be added to achived total amount of fuel required for flight.

Aircraft fuel tank in general devided in to 3 main area, inside both wings itself as well as under the fuselage which is inside the body of the aircraft itself. Fuel tank in the wings will be filled up first before the fuselage. If happen that you sit in the middle of the aircraft next to the wing area, take not that below your feet is where the fuel tank is located.

Hydraulic System Transfer

Hydraulic system on B 737 divided into 3 system which is A, B & Standby however only A & B system quantity shown in the system page on lower display unit. Standby system reservoir is connected to system B.

It can happen that few amount of hydraulic fluid did transfered to one another during flight even though theoretically it's not posible. It can happen through movement of shuttle valve that connect both system together when it supplied as back-up such as alternate brake. To normalise it back basically we need to drain it and replenish another system system with new fluid.

Experienced 737 engineer know the trick to transfer it with-out to drain and topping-up. Here i would like to share you the trick. From the photo we can see system B is higher, now to transfer from B to A.

1. Turn on B emdp pump.
2. Set park brake.
3. Turn on A emdp pump.
4. Turn off system B pressure by operate the flight control
5. Release park brake.
6. Turn off system A emdp pump.

After few repetition we can see the fluid transfered to another.

* This is just for information sharing and not to replace the aircraft maintenance manual procedure.

Landing Gear Shock Strut Leakage.

During all this years i'm working on B737 NG, leakage on the main and nose landing gear strut is common on all aircrafts that i've worked with either Mastar or on current fleet.






I'm sure if someone unfamiliar with this situation will thinked that the this landing gear is having a problem of leakage however it is not.






As per Boeing Maintenance Tip document, this is because of new design on new 737 landing gear, thin layer of oil presence everytime the shock strut extended and this layer plus dirts that have sticked to it has been push down by a scraper seal as the shock strut compressed.


A follow-up maintenance action have to be carry-out after few hundred hours of aircraft operation, this is to ensure sufficient amount of fluid remain in the shock strut itself.

BBJ Winglet

Earlier BBJs was delivered without the winglet because it is still waiting for FAA approval. Now all BBJ delivered to customer with the winglet. Earlier BBJ have to go to winglet installation center like Patts Aviation in Wichita to get it installed, however nowadays there are few more maintenance organization approved by Boeing to carry out the installation like Malaysia Airlines Engineering in Kuala Lumpur.

Winglet mainly gave two major benefits, to reduce drag created by turbulence of airflow at the wing tip during flight thus provide fuel efficiency for longer flight range. Second benefit is cosmetic wise. It gave more corporate look for this VVIP aircraft. Imagine this BBJ without winglet, does it looks like corporate VIP aircraft? I don’t think so.

Below is the technical summary from Boeing website.

Blended winglets offer operational and economic benefits to BBJ and 737-800 customers. Mission block fuel is improved approximately 4 percent. Range capability is increased by as much as 200 nmi on the BBJ and 130 nmi on the 737-800 commercial airplane. The reduction in takeoff flap drag during the second segment of climb allows increased payload capability at takeoff-limited airports.
Environmental benefits include a 6.5 percent reduction in noise levels around airports on takeoff and a 4 percent reduction in nitrogen dioxide emissions on a 2,000-nmi flight.
The blended winglets now are available as standard equipment on BBJs, as optional equipment on 737-800 commercial airplanes, and by retrofit for BBJs, 737-800, and 737-700 commercial airplanes already in service. Because the winglet structure and systems follow established maintenance intervals and life cycles, winglets have a minimal effect on airplane maintenance.

What is BBJ?

I should put this as my first posting, not all know what BBJ is. Well it basically a glorified 737NG (next generation). NG series is -600/700/800/900. There is 2 type of BBJ, BBJ1 & BBJ2. BBJ1 basially a 737-700IGW (inreased grosss weight) due to it has a 737-700 fuselage with 737-800 wing's and center section so that's why IGW is there.

To cater for VIP needs for comfort (larger space onboard their private jet) plus longer range, Boeing with joint venture with General Electric has come out with the idea to sell this type of aircraft, BBJ1 in 1996 & BBJ2 in 1999. With additional fuel tanks in the cargo area, more fuel can be add up thus providing longer range. But of course it is give and take between range and payload. If you want more baggage space & more seats the range will be shorter than max fuel tanks in cargo with less passanger. For instance, max range with 8 vip onboard plus full fuel tanks can go up to 11,000km in range, basically from London to LA, Kuala Lumpur or Tokyo with ease.

The BBJ that came out from Boeing plant will be green aircraft ie without interior/cabin equipment. First it will be sent to Patts Aviation in Wichita, USA for auxiliary fuel tank installation. Depend on customer preference, the aux fuel tank which is basically like a cargo box will be installed in forward or aft cargo or maybe on both side. After that it will be sent to outfitting center furnish the cabin as per customer requirement. The very popular outfitter is Jet Aviation in Basel, Switzerland, very well known with their high quality workmanship.

After several months the aircraft will be delivered to their customer with their custom fit cabin. Sofas, full size bed (plus massage), showers, full size galley, big plasma TV with full surround sound, as per customer request, just name it but of course it will come with a price, not a problem if you are a billionaire.