Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
HQ-18-17 R1
October 9, 2020
This is information only. Recommendations
aren’t mandatory.
Introduction
This revised Special Airworthiness Information Bulletin (SAIB) updates
aircraft operators, Fixed Base Operators (FBOs), FAA repair stations
and Flight Standard District Offices (FSDOs), and foreign civil
aviation authorities with recent actions and recommendations taken by
Airlines for America (A4A) and other aviation industry stakeholders to
inhibit or prevent the migration of Super Absorbent Polymer (SAP)
filter media particles into aircraft fuel supplies. The SAP media is
the filter element material utilized in ground-based water filtration
systems called filter monitors to absorb water from the fuel before it
enters the aircraft.
A4A issued Bulletin 2017.2, “Modified ATA103 Requirements for Filter
Monitors”, dated December 11, 2017, and Bulletin 2018.1, “Update on
ATA103 Requirements for Filter Monitors,” dated June 5, 2018,
describing six actions intended to inhibit or prevent the migration of
SAP media into the fuel supply. In addition, the Energy Institute (EI)
published a bulletin in December 2017, “IATA Super-absorbent Polymer
(SAP) Special Interest Group – Data summary and proposed roadmap,”
describing the work of that group and associated recommended preventive
measures. The recommended actions in the A4A bulletins include limiting
the maximum filter monitor differential pressure to 15 psi, replacing
filter elements with the newest edition elements, and cleaning of
hose-end nozzle strainer screens using an improved procedure. The EI
bulletin describes the same actions but has not been updated with the
current target dates for completing the recommended actions. The EI
bulletin also describes a plan for the eventual replacement of filter
monitors with new technology filtering systems within the next three
years.
The Joint Inspection Group (JIG), A4A, and the International Air
Transport Association (IATA) issued Bulletin, “Joint Industry Field
Trials: Impacts of the COVID-19 Crisis and Withdrawal of EI1583
Specification,” dated May 26, 2020, to alert the aviation fuel
community of delays in the introduction of alternative filter
technologies and provide recommendations for the continued use of
filter monitors beyond December 31, 2020, if necessary.
A4A issued Bulletin 2020.3, “Dirt Defense Filtration with Electronic
Water Sensors,” dated August 2020, to provide information on the use of
this recently introduced filtration system. This filter technology may
be appropriate for use for refueling operations in certain locations.
This SAIB recommends that aircraft operators, FBOs, FAA repair
stations, FSDOs, and foreign civil aviation authorities review the
information described above with aircraft re-fueling operators for
compliance with the recommended actions.
At this time, the airworthiness concern is not considered an unsafe
condition that would warrant airworthiness directive (AD) action under
Title 14 of the Code of Federal Aviation Regulations (14 CFR) part 39.
Background
Filter monitors are constructed as cylindrical vessels that contain
approximately 25 to 35 cylindrical filter elements. The active media in
the filter elements is SAP, which absorbs water from the fuel as it
flows over the element. Filter monitor manufacturers qualify their
products to an industry specification published by the Energy
Institute: EI 1583, “Laboratory Tests and Minimum Performance Levels
for Aviation Fuel Filter Monitors.”
The concern with SAP migration had existed since the early 2000’s when
airlines had to reduce their aircraft fuel filter replacement intervals
due to an increase in reported fuel filter bypass incidents and the
U.S. Air Force (USAF) experienced engine flameouts caused by SAP
clogging of engine fuel filters. The USAF concluded that the use of
Fuel System Icing Inhibitor in jet fuel could induce SAP media
migration into the jet fuel loaded on to the aircraft and permanently
removed filter monitors from their ground refueling operations. The
civilian fleet of aircraft continued to use filter monitors, but an
industry investigation was initiated in response to the fuel filter
replacement reports. As a result of the industry investigation, in 2009
the 6th edition of EI 1583 added a test intended to identify filters
that were prone to SAP migration.
The concern was renewed in April 2010, when a Cathay Pacific Airlines
Airbus A330 aircraft experienced engine control problems that resulted
in an emergency landing. The incident was determined to be caused by
SAP contamination of the aircraft fuel system due to an over
pressurization of the filter monitor during aircraft refueling. Since
this incident, there have been seven additional aircraft events where
investigators determined SAP was the cause of operability issues for
the aircraft operator.
Bench testing of the current design filter monitor elements has shown
that they can release SAP, particularly at differential pressures above
15 psi under normal operating conditions, and filter monitor
manufacturers and SAP manufacturers cannot guarantee that trace amounts
of SAP will not pass downstream of filter monitor elements when in
service. However, recent service experience has shown that the
mitigating actions recommended in A4A Bulletin 2017.2 may be sufficient
to reduce the risk of contamination until alternative filter
technologies are made available.
The first replacement filtration technology that has been qualified for
use by industry is the dirt defense filter with electronic water
sensor. This filtration system is currently being introduced into
service.
The FAA is monitoring the situation to determine if additional action
is required. The agency requests that any service difficulties and
maintenance and inspection findings on aircraft that are suspected of
experiencing SAP contamination should be reported to us in support of
this effort.
Recommendations
The FAA recommends the following:
Review A4A Bulletin 2017.2,
“Modified ATA103 Requirements for Filter Monitors,” dated December 11,
2017, and Bulletin 2018.1, “Update on ATA103 Requirements for Filter
Monitors,” dated June 5, 2018, with aircraft re-fueling operators for
compliance with the recommended actions described in the bulletin. The
bulletins are attached for your reference.
Review EI bulletin “IATA SAP
Special Interest Group – Data summary and proposed roadmap,” published
in December 2017, with aircraft re-fueling operators for additional
information relating to this issue.
Review industry bulletin
“Joint Industry Field Trials: Impacts of the COVID-19 Crisis and
Withdrawal of EI1583 Specification,” dated May 26, 2020, for
information on the continued use of filter monitors and the delayed
introduction of alternative filter technologies.
Review A4A Bulletin 2020.3,
“Dirt Defense Filtration with Electronic Water Sensors,” dated August
2020, for information on the use of the recently introduced dirt
defense filter with electronic water sensor filtration system.
For Further Information Contact
Mark Rumizen, Senior Technical Specialist, FAA, 1200 District Avenue,
Burlington, MA 01803; phone: (781) 238-7113; mobile: (781) 402-4609;
fax: (781) 238-7199; email: mark.rumizen@faa.gov.