Bjorn’s Corner: Keeping airliners operational. Part 8

By Bjorn Fehrm

June 09, 2017, ©. Leeham Co: This week we continue our analysis of the operator’s maintenance plan we made last week for our tentative airline.

Our airline is using Airbus A320s as our operational airplane. For these aircraft we have completed a maintenance plan based on the aircraft OEM’s Maintenance Planning Document (MPD) as well as other regulatory requirements.

Figure 1. The first modern maintenance program was formed around the Boeing 747. Source: Wikipedia.

Maintaining our aircraft

We as the aircraft’s operator are solely responsible for keeping our aircraft airworthy. Our local Airworthiness Authority is the surveyor, assuring that our Operator’s Approved Maintenance Plan (OAMP) and our maintenance jobs are conforming to their rules.

Maintaining an airliner in a conforming way is no cheap proposition. Our mechanics and any external companies doing the jobs need certification for the jobs. It’s extremely important that all tasks are done in a correct way. An incorrectly replaced part in, for example, the flight control system, can be fatal for the aircraft.

That is why everything is done by specially trained personnel and jobs done are regularly controlled by the authorities.

Cost for maintenance

Here follow some cost examples for the different maintenance actions we described last week. Airlines calculate the cost for each job and then spread it over the aircraft’s operational block hours. Maintenance cost provisions are then accrued on a Flight Hour basis according to the calculations.

Line and Ramp check costs

Line and Ramp checks are the cheapest to perform but there will be many of them over a year. Spread over our 3,500 Flight Hours, we calculate $250 to $300 average cost per Flight Hour.

A checks

The A check costs more to perform but are only done every 600 Flight Hour or 450 Flight Cycles. We would typically do the check after 400 Flight Cycles. This means, with 2,450 flight cycles per year, we will do six A checks per aircraft and year.

The check in itself takes about 80 work-hours to perform. To this will be added nonscheduled repairs and cabin cleaning tasks. With material consumption added, we calculate $30 to $40 per Flight Hour for the A checks.

Base checks

The C checks and D checks often are grouped together for cost, as the tasks from the structurally-oriented D checks (a heavy six- and 12 years check) are clustered together with the C checks, which happen around these calendar times. They are then collectively called Base checks.

To understand the Flight Hour cost, we calculate the cost all the work-hours and material consumption for each check in a complete cycle of C checks (C1 to C8) where D check tasks have been added. Then we divide with the flight hours we would have flown during this time.

To this total cost are added costs for expected Service Bulletin and Airworthiness Directive work, a provision for non-planned corrective actions as well as refurbishing costs for the aircraft’s interior and exterior.

This all accrues to us reserving $170 and $190 per Flight Hour for the C and D checks.

Heavy items

During the Ramp and Base checks several expensive subsystems like Wheels/Brakes, Landing gear, Thrust reversers or APU are treated separately costs wise.

These so called “Heavy Items” are calculated as own cost items with the engines. We will look at these costs in the next Corner and then look at the total airframe and engine maintenance costs for our airline.

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