In response to customer
requests to improve maintenance programs for out-of-production airplanes,
Boeing initiated an effort in 1999 to update the maturing maintenance
program for the 747-100/-200/-300 (i.e., 747 Classic). Because the
747 Classic and 747-400 are structurally similar, Boeing and the
industry decided to update the maintenance program for the 747-400
at the same time.
The revised maintenance
requirements comply with industrywide maintenance practices developed
by the Air Transport Association (ATA) Maintenance Steering Group
(MSG), a group of airframe manufacturers, airlines, U.S. Federal
Aviation Administration (FAA) representatives, and suppliers. These
MSG Level 3, Revision 2 (MSG-3 Rev. 2) standards are the same as
those used to develop scheduled maintenance requirements for the
777, 737-600/-700-/800/-900, and 717. MSG-3 Rev. 2 methodology also
was used to update maintenance programs for the MD-80, DC-9, DC-10,
and DC-8 during the late 1990s. Updated maintenance programs for
the 727 and 737-200/-300/-400/-500 are scheduled for completion
by year-end 2002 and third-quarter 2003, respectively.
Two industry steering
committees (ISC) were formed in 1999 to revise the 747 maintenance
programsone for the 747 Classic and the other for the 747-400.
Each ISC was made up of representatives from 747 operators, Boeing,
and the FAA. More than 50 percent of the 747 Classic fleet and 70
percent of the 747-400 fleet were involved in the three-year effort.
The resulting 747 Classic and 747-400 Maintenance Review Board Reports
(MRBR), which have been approved by the FAA, can help 747 operators
significantly reduce maintenance costs. Based on data reported by
operators using MSG-3 Rev. 2 maintenance programs for the MD-80,
DC-9, DC-10, and DC-8, annual savings for 747 operators could be
as much as 30 percent. Savings are achieved through
intervals between maintenance checks.
of redundant and inefficient maintenance tasks.
packaging of maintenance requirements.
commonality between models.
requirements for the 747-400 systems
and power plant.
methods of compliance to corrosion
INCREASED INTERVALS BETWEEN MAINTENANCE CHECKS
Under the revised MRBRs,
747 operators can perform extensive maintenance inspections (i.e.,
letter checks such as D-checks) less frequently (table
1). This allows operators greater airplane utilization between
Increasing the intervals
between scheduled maintenance checks was supported by significant
operator in-service data gathered during the MSG-3 Rev. 2 analysis.
In addition, the flight-hour parameter for D-checks was eliminated
because data indicated that the parameter had a minimal effect on
the maintenance tasks performed during those checks.
ELIMINATION OF REDUNDANT AND INEFFICIENT MAINTENANCE TASKS
During the MSG-3 Rev.
2 analysis of the 747 Classic and 747-400 MRBRs, the ISCs identified
and eliminated redundant maintenance tasks in the areas of systems
and power plant maintenance and structures maintenance. The 747
Classic ISC also added a zonal maintenance program for the 747 Classic
that complies with MSG-3 Rev. 2 standards.
and power plant maintenance.
The following systems and power plant maintenance tasks were identified
as redundant or inefficient: the escape slide testing cycle for
both the 747 Classic and 747-400, condition monitoring and on-condition
maintenance control processes for the 747 Classic, certain FAA-mandated
tasks for the 747-400 that had not been analyzed using the MSG-3
process, and several general visual inspection (GVI) tasks for the
747 Classic and 747-400
escape slide testing cycle. The three-year cycle for testing
the emergency escape slides on both the 747 Classic and 747-400
was extended to a 12-year cycle. Because escape slide inflation
is costly and time consuming, this change offers operators significant