A lot has already been written about airplane lifespan, maintenance and dismantle topics. Still, I decided to summarize some of them and what I learned while searching for original parts. At the end this topics are sort of basis for any genuine part cockpit builder! Unfortunately as long as they work or fly they are not available or better unafordable!
Airframe lifespan
Airplanes basically have two lifespans, airframe lifespan and economic lifespan. Airframe lifespan is determined by the manufacturer with designing cycles (pressurization cycles). Passenger planes are typically designed for 40,000 flight cycles or 60,000 flight hours (A320) with some differences among short and long haul. Pressurization cycles cause stress to fuselage and wings witch over time develop cracks around the fastener holes due to metal fatigue. In general airliners lifespan is around 25 – 30 years and during that time they have periodic maintenance checks.
Maintinance
A check, a light check every 500-600 flight hours or 200–300 cycles in a sequence of checks (A1, A2, A3, etc.), aircraft specifics. Checking and servicing oil, filter replacement, lubrication, operational checks, and equipment inspection.- B check, usually performed in a series of A1 to A12 checks, additional operational and functional checkouts, approximately every 6-8 months.
- C check, approximately every 20–24 months or 2000 cycles (aircraft specifics). Can be done in series of shorter checks (C1, C2, C3, C4, etc.). Covers intense functional and operational systems checks with minor structural corrosion and crack inspection, various upgrades and service bulletin requirements.
- D check, a heavy maintenance check, approximately every 6-12 years (aircraft specifics). All phased C check program (light and heavy) can replace a single D check. Aircraft is taken apart completely for in depth structural inspections. Engines with pylons, apu and landing gear are removed for check and possible repair/overhaul. Flight controls and part of outer paneling is also removed for metal skin and structural inspection.
Nowadays maintenance checks lettering is less important as checks get more task orientated and grouped into block maintenance packages/programs of shorter checks ( C-Light_C1, C-Heavy_C1-C2, … ) that are more efficient for the airlines.
Of course airframe lifespan can be additionally stretched by special inspections and lifespan extension maintenance programs like Airbus Extended Service Goal (ESG). ESG I for A320 will extend lifespan to 60,000 cycles and 120,000 h and with ESG II to 90,000 cycles and 180,000 h.
Economic lifespan
Some times still airworthy planes get scrapped, that is when economic lifespan gets into play. Good maintenance programs can extend airframe lifespan but with age it will get more expensive and usually airplanes get scrapped for economical reasons! Economic lifespan is mainly determined by the operating cost that are shaped by various factors. One of the most important ones are the fuel prices which will strongly influence the airline’s operating cost and finance. When fuel prices are low, older (less fuel efficient) airplanes can still fly economically. With low fuel prices also MRO’s will have more work servcing
older planes that need more maintenance. Globally growing air traffic demand is also somewhat forcing airlines to keep their older planes for longer as deliveries of new planes struggle to keep up with the growth.
When fuel prices get higher this story turns and the number of new airplanes will start to grow as they are cheaper to operate concerning fuel and maintenance. At the same time the value of older airplanes will drop as they are r032emoved from service in larger numbers. With low aircraft prices dismantle becomes an interesting economic alternative. Financial calculations will lead owners to conclusion that airplane disassembly and dismantle generates more than keeping it in operation through a lease contract. Engine condition and upcoming heavy C or D checks are also contributing factor in this decision making!
Disassembly and dismantle
Regardless of the reason, airplane removed from the service and destined for dismantle is still a valuable asset worth a lot of money. The early A320 models (1990-95) values where around $6-7 million as a tear down in 2008, prices for younger airframes (2005-10) of course grow steeply to $30-40 million. Disassembly is interesting because of salvaged aircraft parts and components like engines, landing gears, APUs, avionics, doors, wing parts,… that are all hot sellers. There is a high demand for engines, in good condition they can reach $1-2 million each and that makes them a core value of airplane.
With proper servicing records and additional repairs or overhaul used parts can be airworthy again, re-certified and returned to service on active airplanes. Overhauled parts will come cheaper than brand new OEM parts. These parts will also need paperwork with complete history and traceability. Furthermore airframes are made out of about 60 percent aluminum, 15 percent steel and 10 percent rare metals like titanium. These scrap metals are also worth something at a weight ratio of 20 – 30 tons.
When decision is made to retire an airplane leasing company or airline will store (additional costs) or usually sell the aircraft to the highest bidder. These are mostly tear down companies, aircraft part retailers or distributors and part overhaulers. When the new owner is known it will make a ferry flight (if in airworthy condition) and land the airplane for the last time at contracted aircraft tear down facility. There this highly sophisticated flying machine will become a source for thousands of parts and at the end a pile of scrap metal and waste material that owner needs to sell or dispose / recycle. First disassembly process starts with removal of batteries and hazardous toxic fluids like fuel, hydraulic and other oils. Next valuable parts and components are removed beginning with engines and followed by flight control surfaces, APU, doors, avionics, air condition parts, recorders, nose cone, fuel pumps, all sort of sensors, array of valves, pilot seats, windscreens, lavatories, galleys,… high value metals. At the end when airplane is stripped of all valuable and usable parts the landing gears are removed. At this moment the airplane is placed on wooden beams/pallets or laid directly on the ground. Cockpit section is usually cut and stored for further simulator use. The rest of the cabin interior is stripped bare in order to make sorting of recyclable materials from waste easier and minimise the environmental impact. Not so long ago airframes where crushed together with everything that was left behind. Well I guess some still do it this way, specially with wide bodies where complete interior removal simply takes too much time and money.
The last thing to do is dismantle or tear down of metal airframe. Fuselage and wings are chewed through and crushed to fragments by wrecking excavator using a giant claw. All that is left is one big piles of recyclable aluminum. Scrap aluminium is somewhat friendly, sustainable material as it can be recycled without a loss of quality. Furthermore in re-melting process it will use just 5% of the energy needed to produce the original aluminum product.
The best recycling I see is cockpit reuse as simulator… I know, that’s only 2% of the entire airplane!
Additional source :
– Flightglobal.com, Flight Airline Business, Special report Values in pieces by Oliver Bonnassies
– Flightglobal.com, Commercial Aviation Online, Talking Scrap by Oliver Bonnassies
– Aircraft Monitor, Basics of aircraft maintenance programs for financiers by Mr. Shannon P. Ackert
– Aircraft Monitor, Basics of aircraft maintenance reserve development and management by Mr. Shannon P. Ackert
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