The document discusses the costs associated with digital avionics systems for civil and military aircraft. It outlines categories of avionics costs such as acquisition costs and operating costs. It also discusses the concept of life cycle cost, which considers total costs from inception through disposal. For civil aircraft specifically, it breaks down formulas for calculating investment cost, which includes installation and spare parts costs, and operating cost, which includes maintenance labor, materials, fuel penalties, and spare parts holding costs over the aircraft's service life. The key relationship discussed is how mean time between failure and life cycle costs are determined based on design quality and data from previous similar systems.

1. Figuring the cost of avionics
Cost of Digital Avionics
 How much does it cost?
 How much to operate?
Avionics cost is important for both civil and military
aircraft but the relative importance of cost is different
between civil and military aircraft
Civil aircraft – avionics cost is as important as the
performance variables such as reliability and weight
Military aircraft – contribution of avionics for mission
success is more important than avionics cost

2. Categories of avionics cost
 Acquisition cost
Ex : original equipments,
initial spares
 Operating cost
Ex : maintenance personal
wages, maintenance support

3. Life Cycle Cost
Life cycle cost (LCC) : total cost for a
digital avionics system from conception
through final disposition
Civil aircraft : two types of LCC
 Investment cost
 Cost of ownership

4. LCC For Digital Avionics

5. Relation between LCC and
MTBF

6. Relation between LCC and
MTBF
The pair of curves should be constructed as
early as possible in design process to
achieve minimum LCC design
To achieve increased MTBF, higher quality
design is increased which in turn increases
design development and testing cost
This relation ship is determined from data
based on predecessor systems of similar
design

7. Life Cycle Cost For Civil Avionics
-Investment Cost
Investment cost :what it costs to put the system in
service
Equation for investment cost
IC = FIC + FSPC + FSUC
FIC = (UC + INS) X QPA X NA
Where UC – unit cost
QPA – installation cost per unit
NA – number of aircraft in fleet ( for a given
operator)
FIC – fleet installed cost
FSUC – fleet support cost
FSPC – fleet spare cost

8. FSPC = ICRS + ICES
where
ICRS – initial cost of rotable parts
ICES – initial cost of expendable spares
ICRS = UC X NS
where NS = number of spares
ICES = MM X NMS/12
Where
MM – maintenance material cost per year per fleet
NMS – number of months of stock in initial
provisioning

9. MM = (NA X UTIL X QPA X FR) X CE
Where
UTIL – flight hours per year per aircraft
FR – failures per flight hour
CE – cost per expendable item
As MM increases the number months of
stock(NMS) decreases to minimize the sum of
reorder and inventory holding cost

10. Operating cost:The important elements of OC are
maintenance labor including direct maintenance
material,direct maintenance labor, fuel penalties and
spares holding
Equation for operating cost
N-1
OC =∑{[ DML X (1 + MBF) + DMM + FP] X
i=0
UTIL X NA + SH} X (1 + INF/100)i
Where
N – service life, years
DML – direct maintenance labor, line and shop,
dollars per flight per hour
Life Cycle Cost For Civil Avionics
-Operating Cost

11. MBF – maintenance burden factor, typically
2< MBF >2.4
DMM – direct maintenance material
INF – inflation rate, percent per year
INF = FP + FCW + FCP
Where
FCW – fuel cost in dollars per flight hour
FCP – fuel cost penalties due to operate the system,
cooling air, and system induced drag penalties