RU33: AECMA 1000D - Goal and Reality
The contribution deals with the
transposition of projects on the basis of the
AECMA-1000D-specification.
The author explains problems which exist
outside aeronautics with the application of
this specification.
What does the AECMA-1000D-Specification
Comprise?
AECMA 1000D is an International Specification
for Technical Publications utilizing a Common
Source Data Base (CSDB).
|
What are the intended benefits of
using the specification?
|
- It is based on internationally agreed neutral standards.
- It reduces maintenance costs for technical information.
- It allows sub-sets of information to be generated to meet specific user needs.
- Transfer of information and electronic output is
facilitated between disparate IT systems.
- Many different output forms can be generated
from the same base data thus ensuring safety
of data and that every user regardless of output
form is getting the same message.
- The AECMA 1000D data module concept can be
and has been applied to legacy data.
- It is Non Proprietary and allows neutral delivery of data and management of data.
- It uses the CALS philosophy of "create once use many".
The basic problems when applying the AECMA
1000D-specification outside aeronautics result
from the development of this specification. It was
conceived for aeronautics from the beginning
and has been developed step by step. Up to the
present time the Document Type Definitions
(DTD) describe aeronautics specific processes.
The specification consists of six basic DTD's:
| (1) | Air Fault - | air fault isolation information data modules |
| (2) | Air Crew - | aircrew data modules |
| (3) | Description - | description data modules |
| (4) | IPD - | illustrated parts data modules |
| (5) | Procedural - | procedural data modules |
| (6) | Schedule - | maintenance planning data modules |
The Description-DTD can generally be considered
usable also outside the area of aeronautics since
one can describe any technical situation with help
of the available elements and attributes. All other
DTD's reflect processes of aeronautics. Above all
the Air Fault-DTD, the Air Crew-DTD and the
Schedule-DTD describe processes that are typical
of aeronautics.
Therefore a transfer to other processes is very
difficult. This should be illustrated by an example:
In the Procedural-DTD, there is the element
PRELREQS (Preliminary Requirements). This in
turn contains the element PMD ( Production
Management Data). PMD contains the element
THI (Threshold Interval) with the attribute UOM
(Unit of Measurement for the Threshold
Interval).This attribute can contain 14 entries:
| FLTHRS | = | Flight hours |
| FLTCYC | = | Flight cycles |
| MONTH | = | Months |
| WEEKS | = | Weeks |
| YEARS | = | Years |
| DAYS | = | Days |
| SUPERCYC | = | Supersonic cycles |
| PRESSCYC | = | Pressure cycles |
| ENGCYC | = | Engine cycles |
| ENGCHG | = | Engine change |
| SHOPVIST | = | Shop visits |
| APUCHG | = | Auxiliary power unit change |
| LANDGCHG | = | Landing gear change |
| WHEELCHG | = | Wheel change |
Under the prerequisite that no DTD-modifications
are planned, this means that these entries have to
be used. Looking at a motor vehicle, a ship or a
radio-station instead of, for example, an airplane,
one recognizes the difficulty of such a transfer.
None of the mentioned examples belongs to the
supersonic area or owns landing gears.
In projects outside aeronautics, many companies
have therefore tried to simplify the AECMA-DTD's
so that one doesn't use many optional elements.
Many projects even use only the Description-DTD
and the Procedural-DTD. From that follows, of
course, that the intended advantages don't result.
Thus the very high expenditure for such projects
is no longer justified.
From the author’s point of view, this
unsatisfactory development is caused by the
following problems:
- The AECMA 1000D-specification is based upon
the CALS-model. As a very complex theoretical
model, it does not portray and insufficiently
processes real economic. Therefore many
projects did not succeed in conveying the
necessary data regarding quality and quantity,
and in the requested time.
- Other problems emerge from the AECMA-organization
and the performance of the
documentation concept. The representation in
the existing modular form is very unclear and,
understandable only with a very high
expenditure for highly qualified specialist
personnel. The concept of creating data
modules is a very good method for processing
data but it shows that there can be problems of
intelligibility. In Germany and Europe, very few
companies can pay such highly qualified
specialists over a long time period.
Furthermore, the permanent postponements in
the development of the specification cause a
lot of problems in the management of such
projects.
- It is not possible to represent all technical
structures and industrial processes with
economically justifiable methods in only
one system.
- The AECMA 1000D specification deals with the
representation and standardization of data.
From the author’s point of view, the consistent
further step is missing; that is, making a
retrieval system available. Experience has
shown that it is no use producing data at very
high costs without knowing exactly how
further processing can take place.
As I have no information on projects, beyond
aeronautics, using the exact specification in full
scope and compatibility in Germany and Europe,
I would be very grateful for comments and
suggestions.
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