9 EUROCONTROL Dominique Colin MAWC 2011 Warsaw

MAWA summit 2011 - Warsaw
Airworthiness issues in every day flight operations -
Application to RVSM
The European Organisation for the Safety of Air Navigation

Outline :
RVSM as an example of airworthiness supporting
operational capabilities
• RVSM operations and RVSM requirements
• Initial airworthiness issues
• Continuing airworthiness issues
• Conclusion
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RVSM
The Reduced Vertical Separation Minimum (RVSM) is the introduction of a 1000-
foot vertical separation standard, or minimum permissible vertical spacing
between aircraft on the same route, from flight altitude 29000 ft (FL 290) to flight
altitude 41000 ft (FL 410), inclusive, in place of the existing 2000-foot value,
introduced in 1958.
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Depiction of RVSM Separation in Abstract
FL360
FL350
MAWA forum Warsaw 2011 Courtesy FAA
4

FL geometric height :
pressure measurement issues
FL 350
FL 340
Constant geometric
height
Curve of Equal Pressure
FL 330
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Elements of total vertical errors
Actual Altitude
Altimetry
System Error
(ASE)
Total Vertical
Error
(TVE)
Displayed Altitude
Flight
Technical Error
(FTE)
Correspondence
Error
Assigned
Altitude
Deviation (AAD)
Transponded Altitude
Assigned Altitude
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RVSM altitude requirements
Example : ASE
• In “Basic” flight envelope
ASE (+3 ) < 200 ft
• In full flight envelope
ASE (+3 ) < 245 ft
Definitions of envelopes and static source error are described in TGL 6 appendix 3
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Depiction of RVSM Separation with safety margins
FL360
245 ft
245 ft
FL350
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TGL 6 RVSM basic requirements
• Safety performance
• Height performance
• Equipage
• Airworthiness
• Training
• Procedures
• Monitoring programme per region
in Europe : EUR RMA EurRMA.Support@eurocontrol.int
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Initial airworthiness issues
Since static pressure measurement is the source for height
estimation, air stream differences between the certified aircraft type
and the actual version must be known and analyzed.
• Down stream modifications may influence static pressure.
• RVSM Type certification is not applicable for other version
unless proven for the new version.
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Basic Compliance Checks for civil aircraft
Is the airframe RVSM MASPS compliant ?
• The compliance method may be applicable to a single airframe or to a
group of aircraft having the same, or similar performance characteristics.
• MASPS compliance documents are typically
• Service Bulletins,
• Supplemental Type Certificates,
• Aircraft Service Changes,
• Type Certification compliant or
• similar regulator approved documents.
• MASPS compliance methods have been formulated to be in compliance
with the requirements contained in the JAA TGL 6 rev.1 or FAA-91 RVSM
and have been verified by flight test before receiving regulator approval.
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Initial airworthiness sources of loss of
compliance
External airframe modifications
Those that affect Static Source Error
• Antennas, sensors, cameras
• Pods/large fairings
• External repairs
• Cargo door installations
Those that affect performance/flight envelope
• Winglets or other wing mods
• Re-engine programs
Hardware modifications
• ADC, flat displays…
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Same aircraft type ?
Cessna C560 Citation
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Same aircraft type ?
Sentinel Astor
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ASE (ft)
ASE monitoring pre and post modification
GLF3 ASE time-series
400
200
0
-200
-400
-600
-800
-1000
9/15/05 3/14/06 9/10/06 3/9/07 9/5/07 3/3/08 8/30/08 2/26/09 8/25/09
Date
Modification
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Continuing airworthiness issues
• Maintenance programme not updated for RVSM
• Maintenance checks failed to be performed
• Pre flight inspections not adapted to RVSM requirements
• Damaged pressure probes
• Clogged static pressure line
• Leaks in static pressure line
• …
• Natural drift with time of the whole altitude measurement chain
( + + + …)(t) : non-programmed maintenance might be
performed triggered from Appointed monitoring units.
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Static ports issues
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Combined Pitot Probe & Static Port
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Static port issues: debris
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ASE
ASE Long Term Drift (example)
150
100
50
0
12-1999 04-2001 09-2002 01-2004 05-2005 10-2006 02-2008 07-2009
-50
-100
-150
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Common Technical Problems
• Damaged Pitot Probes/Static Ports
• Air Data Computers out of calibration
• Aircraft modifications not evaluated
• Sticking Angle of Attack vanes
• Leaks in pitot/static system
• Paintwork within “sterile” RVSM area not to specification
• …
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Conclusion
• Airworthiness is not a fancy engineer activity; it is a necessary
investment to achieve many operational capabilities
• Airworthiness is mentioned in many (if not all) operational capability
mandates
• Any modification (airframe, system) can have a severe impact on
performance
• Operational approval must be documented
• Maintenance programme must be adapted to new operational
capability.
• Monitoring programmes are providing the necessary oversight on
safety level. Follow-up activities once approval is granted.
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Questions ?
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