Industry guidance on monitoring and control of microbial contamination in the aviation fuel supply chain DLA Energy Worldwide Energy Conference Gaylord Convention Center April 11th 2017 Leon O Malley, Ph.D Laboratory Manager ECHA Microbiology Ltd. United Kingdom
Presentation overview Microbiological Contamination Overview of problem Options for control Monitoring Field based monitoring Ideal properties of testing methods Available test method overview
Microbiological Contamination
The Microbial Growth Triangle FOOD; Fuel & Oil Additives Other Contaminants MICROBES MICROBIAL GROWTH SPOILAGE & CORROSION WATER Control!!
Types of Microorganisms Bacteria Yeasts Molds 10 mm bar Fungi All types may be involved in a single incident, simultaneously or in succession.
Manifestation of the Problem Leopard Skin Spotting Of Fuel Coalescer Elements Slime in Jet A-1 Storage Tank Biofilm on Tank Surfaces Pitting Corrosion by SRB in Fuel Pipe
Monitoring
Risk Based Routine Monitoring IATA recommends limit values for microbiological contamination in aircraft fuel tanks. IATA limit values as such are not appropriate in the fuel supply chain; e.g. A heavy contamination from a sump sample in a supply tank is not necessarily a confirmation that fuel supply is unfit for service. JIG Bulletin 83 / Technical Information Document recommends; 1. Evaluate normal background levels; e.g. Initial testing program over 1-2 years. 2. Monitor for change; Routine testing at defined sample points and frequencies according to risk assessed from; Initial testing. Operational experience. Operating conditions (temperature, humidity, risk of water ingress etc.).
Risk Based Routine Monitoring
Risk Based Routine Monitoring Item Sampling location Sampling Frequency High risk facilities Fixed Storage Tanks Moderate risk facilities Low Risk facilities Storage Tank sump drain line or dead bottom sample Monthly 3-6 monthly advisable. Annual monitoring after initial (at least) quarterly screening for 12 months to determine background contamination level Product Recovery Storage Tank sump Tanks drain line or dead bottom sample Monthly 3 monthly. Quarterly where visual inspection is not possible Defuelling Vehicle Vehicle Tank sump drain Monthly line 3 monthly 6 monthly for vehicles routinely used for defuelling
Risk Based Routine Monitoring When interpreting results always consider; Trends, Operational data / experience Monthly test of tank bottom fuel by ASTM D7978
Visual Assessment is the Primary Check Cling film like lacy material (bacterial polysaccharide) at fuel - water interface. Fungal Growth at the fuel-water interface for Jet A-1 fuel Further Contamination Spore (hydrophobic) Best Samples are Tank Bottoms, Filter Sump, Low Point etc. However, significant microbial contamination may not always be seen!
Ideal Properties of a (Field) Microbiological Test Method Reliable Reproducible ASTM Precision Statement Sensitive Detection Limits Wide Range of Detection Training required? Bacteria, Yeasts, Moulds (SRB) Cost effective Rapid Relatively Speaking
IATA Recommended Test Kits for Aircraft Operators Fuel and Water Phase ASTM D7978 (MicrobMonitor2) Growth Method in Nutrient Gel ASTM D7463 (Hy-Lite Jet A-1) ATP detection by Bioluminescence ASTM D8070 (Fuelstat Resinae PLUS) Immunoassay type method Water Phase only Dip slides San-AI Biochecker FC (Bacteria and Fungi) Easicult TTC (Bacteria) Easicult M (Fungi) Only approved for WATER samples!
ASTM D7978 (ECHA Microbiology MicrobMonitor2 ) Technology Growth of Microorganisms in Nutrient Gel and Counting of Resultant Colonies Detects Bacteria, Yeasts, Mold Growth, Spores Equipment Basic Incubator Speed 1 to 4 days Units CFU/L
ASTM D7463 (Merck Hy-Lite Jet A-1) Technology ATP Detection in Water Phase or Water Drops by Extraction Method Detects Bacteria, Yeasts, Mold Growth (not Spores) Equipment Meter Speed < 10 minutes Units Relative Light Units
Laboratory Reference Methods Filtration methods IP 385 and ASTM D6974 (technically similar) are considered by IATA to be the reference methods. Microscope methods can be used for investigation eg Light Microscopy or fluorescent microscopy using stains/probes (FISH). Molecular based profiling methods to assess microbiological diversity
Molecular Methods Culture Sequencing Standardized method between labs Many elements may differ e.g. DNA extraction, PCR primers etc. Bacteria and Fungi Bacteria (and Fungi possible, but needs the correct target gene) Identification requires many manual isolation steps Less time required (Once methodology optimised) Live Microorganisms Live and Dead Microorganisms Limited Spectrum of Wider Spectrum of Microorganisms Microorganisms Percentage of so-called unculturables?
Comparison of Culture and Sequencing Techniques White et al (2011) AEM Vol 77 (13) p. 4527 Cultivation DGGE Pyrosequencing a-proteobacteria 13.8 % 3.9 % 6.6 % b-proteobacteria 21.1 % 19.2 % 45.0 % g -proteobacteria 42.8* % 53.9 % 32.1 % Bacilli 11.8 % 15.4 % 5.1 % Total 89.5 % 92.4 % 88.8 % * High Pseudomonas Denaro et al (2005) Wright-Patterson Air Force Base/Uni of Dayton Direct PCR Cultivation Both 61.9% 4.8% 33.3% Culturing can detect a significant proportion of microbial contaminants Power of molecular methods for investigative work
References Aviation Fuel Industry Guidance Aircraft fuel tanks IATA Guidance Material on Microbiological Contamination in Aircraft Fuel Tanks 5th Edition December 2015. Aviation Fuel Supply Chain - US API RP 1595 Design, Construction, Operation, Maintenance, and Inspection of Aviation Pre-Airfield Storage Terminals. 6 month check of storage tank bottoms by microbial test. A4A 103 Standards for Jet Fuel Quality Control at Airports. Microbial testing recommended if there are indicators of microbial growth (e.g. during tank inspection).
References Aviation Fuel Industry Guidance Aviation Fuel Supply Chain RoW (EI/JIG) EI / JIG 1530 Quality Assurance Requirements for the Manufacture, Storage and Distribution of Aviation Fuels to Airports. JIG Guidelines for Aviation Fuel Quality Control & Operating Procedures for Into-plane Fuelling Services (JIG 1), Airport Depots (JIG 2) and Smaller Airports (JIG 4). JIG Bulletin 83 and Technical Information Document issued October 2015
Thank you for your attention!!