Aircraft Component Groups
The recognized groups of aircraft components are listed in exhaustive detail in the ATA’s publication. This section presents consolidated, generalized groups (for both civil and military aircraft) suitable for studies in the conceptual design phase. Both aircraft classes have similar nomenclature; the difference in military aircraft is
described in Section 8.6.2. Each group includes subgroups of the system at the next level. Care must be taken that items are not duplicated – accurate bookkeeping is essential. For example, although the passenger seats are installed in the fuselage, for bookkeeping purposes, the fuselage shell and seats are counted separately.
8.6.1 Civil Aircraft
Structure group (MstR = Mfu + Mw + Mht + MvtMn + Mpy + Muc + MmiSC)
• Fuselage group (Mfu)
• Wing group (Mw): includes all structural items (e. g., flaps and winglets)
• H-tail group (Mht)
• V-tail group (Mvt)
• Nacelle group (Mn and Mpy) (nacelle and pylon)
• Undercarriage group (MuC)
• Miscellaneous (MMisC) (e. g., delta wing)
The basic structure of the aircraft – the fuselage shell (seats are listed separately under the Furnishing group) is as follows:
Power plant group (Mpp = Me + MtR + MeC + Mfs + Moi) (8.7)
• Dry-equipped engine (Me)
• Thrust reverser (MtR)
• Engine control system (MeC)
• Fuel system (Mfs)
• Engine oil system (Moi)
The power plant group comes as a package, with all items dedicated to the power plant installation. These are mostly bought-out items supplied by specialists:
Systems group (Msys = Mecs + MFc + Mhp + Melec + Mins + Mav) (8.8)
• Environmental control system (MeCs)
• Flight-control system (MFC)
• Hydraulic and pneumatic system (Mhp) (sometimes grouped with other systems)
• Electrical system (MeleC)
• Instrument system (Mins)
• Avionics system (Mav)
The systems group includes a variety of equipment, all vendor-supplied, bought-out items:
Furnishing group (Mfur = Mseat + Mox + Mpn) (8.9)
• Seat, galleys, and other furnishings (Mseat)
• Oxygen system (Mox)
• Paint (Mpn)
Most of the weight is in the fuselage, yet the furnishings are itemized under different headings. Paint can be quite heavy. A well-painted B737 with airline livery can use as much as 75 kg of paint:
• This is a margin to allow unspecific weight growth (Mcont).
The MEM is the total of the previous twenty-two items. This is the weight of the complete aircraft as it comes off the production line to be come airborne for the first time.
Add the following items to the MEM to obtain the OEM:
• Crew: flight and cabin crews (McREw)
• Consumables: food, water, and so forth (Mcon)
The OEM is when the aircraft is ready for operation.
Add the payload and requisite fuel to obtain the MRM. At the takeoff point at the edge of the runway, the MRM becomes the MTOM = (MRM – taxi fuel):
• Payload (Mpl) (passengers at 90 kg per passenger, including baggage)
• Fuel (MfuEl) (for the design range, which may not fill all tanks)
MTOM: The aircraft at the end of the runway is ready for takeoff. The civil – aircraft MTOM is the total weight of all component groups, as shown in Equation 8.10.
The MTOM = f M(x) dx = J2Mi, where the subscript i stands for each component group listed previously.
For civil aircraft, the MTOM is equal to
( Mfu ) + ( Mw) + ( Mht) + (Mvt) + (Mn) + ( Mpy ) + ( Muc ) + ( Mmisc )
+ ( Me) + ( Mtr) + ( Mec) + ( Mfs) + ( Moi ) + ( Mecs) + ( Mfc ) + (Mhp)
+( Melec ) + ( Mins) + ( Mav ) + ( Mseat ) + (Mox ) + ( Mpn ) + (Mcont)
+ ( Mcrew ) + ( Mcons) + Mpl + Mfuel (8.10)