Into-Plane Sampling Procedures (Must Read)

Did you know that up to 80% of aviation fuel quality issues can be traced back to improper handling and sampling procedures? Into-plane sampling Procedures are critical processes that directly impact aircraft performance, safety, and operational efficiency. Contaminated fuel can lead to substantial operational disruptions, potentially costing thousands of dollars per hour for grounded aircraft.

However, there’s good news. Effective into-plane sampling procedures can reduce the risk of fuel contamination by up to 90%. Consequently, understanding proper fuel sampling techniques and quality control measures is essential for maintaining the highest safety standards in aviation operations and confirming fuel cleanliness verification. In this comprehensive guide, you’ll learn about essential sampling equipment, step-by-step procedures, visual inspection methods, and regulatory standards that ensure aviation fuel quality and safety during the fueling process.

Essential Aviation Fuel Sampling Equipment

Proper equipment selection forms the foundation of adequate aviation fuel sampling. Each tool plays a specific role in maintaining fuel integrity throughout the supply chain.

Standard Fuel Sampling Equipment and Containers

Aviation fuel sampling requires specialized equipment designed to prevent contamination and ensure accurate results. The industry standard includes sampling kits with conductive containers that safely dissipate static charges through bonding cables.

Furthermore, all sampling apparatus must eliminate copper and copper-based alloys as these can degrade fuel thermal stability even at very low concentrations. Aviation fuel filtration systems play a crucial role in maintaining fuel quality throughout the sampling process.

Closed Circuit Sampler

Closed-circuit Samplers, also known as ‘Visijars,’ have inlet and outlet valves to control the container’s filling and emptying. The sampler base is usually conical and incorporates the fuel inlet and outlet. The fill port is designed to cause the fuel to swirl around the sides of the clear glass tube. The circuit sampler may also contain a hydrometer and chemical water detection ports.

They are clear glass containers with a lid permanently connected to a sample point to help perform the Visual Appearance Check and other field quality control testing. Their use is increasing for drawing samples, particularly during aircraft fuelling operations. Procedures for sampling into a ‘Visijar’ must ensure a good flow velocity from the source. This is usually achieved by taking a line sample (e.g., opening the sampling valve while the fuel still flows).

Clear-and-Bright Visual Testing Procedure

ASTM D6986 Free Water, Particulate, and Other Contamination in Aviation Fuels (Visual Inspection Procedures), known as the ‘clear and bright’ test (C&B), visually examines fuel for water droplets and dirt particles. The “Clear and Bright” test remains a fundamental visual verification method for fuel quality. This procedure requires transparent containers, typically glass, that allow the examination of fuel against light sources. A white porcelain bucket provides optimal contrast for detecting dye contamination or unusual discoloration. However, this test has limitations as the human eye cannot detect droplets smaller than 40μm, making it practical only for significant contamination causing haziness.

Despite this, it remains a valuable quick-check method. A critical precaution in performing this test is to ensure the sample test jar is clean. This may seem obvious, but there have been many instances where dirty, unsuitable containers have been used, leading to incorrect assessments.

Appearance Photographs

A series of standard photographs of the bar chart through samples of different haze levels, numbered from one through six. Place the bar chart directly behind the container, with the lines toward the container and parallel to the container’s bottom. The narrowest line should be at the bottom of the chart. Photograph No. 1 is the clearest, while No. 6 represents the densest haze (see ASTM adjunct ADJD417602). A fuel sample rated clear and bright will have a rating of “one.”

NOTE: This chart should be printed on high-quality glossy photo paper for accuracy.

Chemical Water Detector Kits: Types and Applications

In its 8th edition guidance, IATA recognizes several proprietary methods for the rapid detection of free water in aviation fuels. Water detection kits identify suspended water that visual inspection cannot detect. The Shell Water Detector consists of a yellow capsule attached to a syringe that changes color when exposed to water. Similarly, CASRI Water Detection Capsules change from yellow to green-blue, with initial indication occurring at low free water levels (< 30 ppmv). Daily testing is required at key points throughout the fuel handling process, including refulling, storage tanks, hydrant filter drains, and refuelers.

Aviation Fuel Particulate Testing Tools

Particulate contamination analyzers provide gravimetric analysis of solid contaminants. These systems typically include glass sand core filters, pressure gauges, and regulators for precise control. Advanced testing equipment can detect particles smaller than 40μm, which may cause significant equipment damage despite being invisible during visual inspection. Comprehensive contamination test kits often combine multiple verification methods, including flash point, density, conductivity, and microbial activity tests.

• • • Understanding Jet A-1 Fuel Specifications and Certification

Step-by-Step Into-Plane Sampling Techniques

Each aircraft refueling needs a cleanliness assessment through quick, simple tests as a final verification of the monitored system. So simple, rapid tests are required to constitute a final check on an intensively monitored and controlled system for the presence of particulate matter and free water, preventing contamination and ensuring aircraft safety.

Pre-Sampling and Safety Protocols

For refuellers, the operator must ensure that the vehicle’s daily sample drains are performed before leaving the depot. Once settled, the low points of the tanks and filters should be drained under pressure and subjected to Visual Check. If these controls are not recorded on the monitoring document, the operator must conduct these checks before proceeding to the apron.

If free water and sediments are confirmed in three successive samples, the vehicle cannot be used for refueling until the Facility Manager has given approval following investigations and remedial actions have been taken. Refuellers must not leave the depot for a fueling operation without confirmation that all necessary drains have been completed.

For the hydrant dispenser, before departing from the depot, the operator must ensure that the daily drains and vehicle samples have been completed. Should these checks not be recorded on the monitoring document, the operator shall perform these controls before heading to the apron. In the event that samples are not taken while under pressure, once the hydrant dispenser is pressurized with the distribution valve closed, a sample must be taken from the filter low point (sump) for a visual inspection before the fuel is delivered to the aircraft.

This additional precautionary measure verifies the absence of free or trapped water and impurities prior to the day’s first aircraft operation or shift. If free water and sediment are detected in three consecutive samples, the vehicle must not be used for fueling until the Facility Manager approves its use following investigations and corrective actions.

Before approaching any fueling equipment, wear appropriate personal protective equipment—including eye protection, gloves, and suitable apparel. Establish a clearly defined fueling zone with the airport authority. Ensure all personnel are familiar with emergency procedures, especially how to summon the Airport Fire Service. Additionally, verify that electrical equipment stays clear of fuel vent points and that suitable fire extinguishers remain readily accessible. Always position vehicles with clear exit paths. These aircraft refueling safety protocols are essential for maintaining a secure operational environment and ensuring proper environmental protection.

Refueller and Hydrant Vehicle Sampling

For refuellers, take a 1-litre sample from the filter outlet after the fuel contained in the delivery line and the body of the filter has been displaced (typically 1000 liters). Conduct an initial inspection with a visual check and CWD tests on this sample. For small volume uplifts, this check should occur post-fueling if the volume isn’t entirely displaced. If the initial sample reveals impurities, water, or any chemical test color changes, promptly take a second sample of at least 1 liter.

Should the second sample exhibit similar issues, halt the refueling process immediately and alert the Station Manager. Communicate with the airline company’s representative to verify the quality of the product meant for the aircraft. No further fuel delivery should occur until the source of the water presence is identified and corrective measures are implemented.

For hydrant servicers or carts, samples must be taken during every fuelling operation for a Visual Check, with at least one sample from each fuelling checked using a chemical water detector. After displacing the fuel in the delivery line and the filter body, typically about 1000 liters, a 1-liter sample is taken from the filter outlet to check for visual contamination and perform a Chemical Water Detector (CWD) check. If water is detected in the initial sample, indicated by a color change with the CWD, a second sample must be drawn immediately. Should the second sample confirm the presence of water, fuelling operations must be halted immediately, and both the hydrant operator/supervisor and the airline representative must be informed.

At the end of the fuelling process, a 1-liter sample should be drawn from the filter separator sump or the inlet side of the vessel under pressure for visual examination. If water is detected in this sample or a color change is observed with the chemical water detector, another sample must be drawn immediately. Confirmation of water presence in the second sample necessitates immediate notification of the hydrant operator/supervisor and the airline representative to prevent the aircraft’s departure. Further deliveries are prohibited until the cause of the water presence is identified and corrective measures are implemented.

Actions on Contamination

• If water or particulate matter is found, draw a second sample immediately.
• If contamination is confirmed, stop fuelling and inform the Station Manager and the airline representative.
• No further deliveries until the cause is determined and remedial action taken.

Sample Requested by Airline

The representative of an airline company may ask for one or more samples to carry out analyses other than the usual visual checks or checks into density. In this case, the following procedure shall apply:

• Determine request reason and analysis type
• Guide sampling process (JET A-1: minimum 2 litres)
• All airline samples must be drawn from the filter vessel’s outlet side
• Keep duplicate samples until Management approval for disposal
• Seal samples with both parties’ signatures by the airline representative and Location Manager
• Notify local aviation management and record details in the sample register.

Proper Sample Collection and Handling

Fuel samples should be disposed of in a suitable container on the vehicle or returned to the fuel storage facility in securely closed sampling containers. Procedures must ensure that fuel samples failing a visual check are not delivered to aircraft and are retained for investigation if needed. Reclaimed fuel must be handled with the same care as aircraft-quality fuel using clean, dedicated containers or equipment. Efforts should be made to remove visible solids and water before transferring fuel into a reclaim tank or returning it to storage, preferably through a filter/water separator. The product obtained from draining and sampling should be returned daily to the depot to remove water and sediment before being returned to storage or downgraded.

A sample-collecting procedure should be established to prevent the mixing of products or grades. An approved written procedure must ensure no contamination when aviation fuel is returned directly to fueling vehicles from product recovery tanks. Many hydrant dispensers have an automatic pump-out function activated by a high-level switch, which returns the fuel from an elevated suction into the vehicle delivery pipework before the filter during fueling, providing an acceptable means of product return. Product recovery tanks should be checked daily for water and sediment. All designated waste tanks, whether standalone or fitted to vehicles, should be clearly marked as “waste fuel (‘slops’) tank – strictly not for aviation use” to ensure they are not used for aviation purposes.

Fuel storage tank sampling is a critical aspect of maintaining fuel quality throughout the supply chain. Regular sampling from storage tanks helps detect potential contamination early and ensures the integrity of the fuel before it reaches the aircraft. Implementing proper fuel sampling documentation procedures is essential for maintaining a comprehensive record of fuel quality throughout the handling process.

Visual Inspection Methods for Fuel Quality Control

Visual inspection serves as your first line of defense in aviation fuel quality control. Mastering these techniques enables immediate identification of contamination issues before they compromise flight safety.

Color and Appearance Assessment Techniques

Proper aviation fuel exhibits a distinct visual profile—jet fuel should appear either colorless or light straw in color. Any deviation from these standard colors often signals contamination. For instance, a reddish or pink tint might indicate cross-contamination with dyed diesel fuel or hydraulic fluid. Always minimize light reflections on the container front when examining fuel samples for optimal contrast. Remember that legitimate jet fuel demonstrates a characteristic “shiny and sparkling appearance” when clean and dry.

The clear and bright test, also known as the C&B test, is a fundamental visual inspection method for assessing fuel quality. This test involves examining a fuel sample in a clear glass container against a light source to check for clarity, brightness, and the absence of visible contaminants. The color rating of the fuel is also assessed during this process, with any unusual coloration potentially indicating contamination or degradation.

Identifying Suspended Water Contamination

Water is the most prevalent and potentially damaging contaminant in aviation fuel. To mobilize contaminants effectively, ensure the highest flow velocity from the source while keeping the flow stable before introducing fuel into the ‘Visijar.’ To detect it, first check for cloudiness or haziness in the sample—this typically indicates suspended water contamination.

Essentially, water in fuel appears in three forms: dissolved (invisible), dispersed (creating haziness), and free water (accumulating on surfaces). Chemical water detection kits offer additional verification, changing color when exposed to water concentrations as low as 15-30 ppm. Manufacturers provide CWD testing accessories for ‘Visijar’ tops, which are available in manual and pneumatic options. Although testing can be done at the top, it’s not optimal, as free water accumulates at the bottom, leading to lower concentrations at the top. For the most precise results, conduct CWD testing right after the Visual Appearance Check to identify any suspended water droplets.

Moreover, you can verify water presence using food coloring: add a drop of food coloring to the sample. If it dissolves rather than settles to the bottom, this confirms water contamination. Free water detection is a crucial aspect of fuel quality control measures.

• • • Understanding Free Water Visibility in Jet Fuel: A Comprehensive Guide

Detecting Particulate Matter in Samples

Particulate contamination in fuel systems often stems from sources like rust, sand, and dust. ‘Visijars,’ especially those used on vehicles, tend to collect these contaminants, necessitating regular cleaning of both their internal and external surfaces to ensure proper function. Facilitating fuel flow into the ‘Visijar’ is crucial by achieving the maximum possible flow velocity from the source while maintaining optimal flow conditions. The valve should be fully opened and left untouched during sampling to preserve the sample’s integrity.

The design of closed-circuit samplers is critical, as they rely on the fuel entering the jar to create a vortex, which is vital for conducting an effective Visual Appearance Check. Any interference with the vortex formation or visibility can compromise the check’s effectiveness. Hence, it is imperative that no accessories disrupting the vortex are used during sampling or the checks. Furthermore, the ‘Visijar’ bottom or drain ball valve must remain closed during sampling and testing to prevent contaminants from being driven into the outlet pipework, which would invalidate the visual inspection. Regularly inspecting the vortex bottom for particles and water droplets is also essential to ensure accurate assessments.

For more advanced fuel contamination detection, some facilities employ membrane color tests. This method involves passing a fuel sample through a special membrane filter, which captures and highlights contaminants for easier visual identification

Regulatory Standards Governing Aviation Fuel Quality

Stringent regulatory standards form the backbone of aviation fuel quality management worldwide. Two primary specifications govern jet fuel quality: ASTM D1655 and DEF STAN 91-91, each with detailed requirements ensuring consistent performance across global operations.

ASTM and DEF STAN Specifications for Jet Fuel

ASTM D1655-24b serves as the cornerstone specification for aviation turbine fuels, primarily used for purchasing contracts by civil aviation authorities. This standard defines two specific fuel types: Jet A with a freezing point of -40°C, primarily used in the United States, and Jet A-1 with a lower freezing point of -47°C, commonly used internationally. In fact, these specifications require rigorous testing of composition, volatility, fluidity, combustion properties, corrosion potential, thermal stability, contaminant levels, and approved additives.

The UK Defense Standard (DEF STAN 91-91) represents another authoritative specification for jet fuel quality. Whereas ASTM is widely adopted in America, DEF STAN 91-91 is more prevalent in Europe and other regions. This specification is generally more stringent than ASTM in several parameters. Key differences include:

• More restrictive limits on certain additives
• Enhanced thermal stability requirements
• Stricter particulate matter controls
• Modified testing methodologies for specific properties

Among industry professionals, the Joint Inspection Group (JIG) is recognized as “the world-leading organization for the development of aviation fuel supply standards.” JIG standards encompass the entire supply chain from refinery to wing-tip, ensuring consistent quality throughout fuel handling processes.

In addition to these standards, the Aviation Fuel Quality Requirements for Jointly Operated Systems (AFQRJOS) Checklist combines the most stringent requirements from both specifications. This harmonized approach ensures that fuel meeting Check List criteria automatically satisfies both ASTM and DEF STAN requirements, facilitating global operations.

Presently, emerging regulations further address sustainable aviation fuel (SAF) integration, requiring suppliers to increase SAF blending with conventional fuels gradually. These blended fuels must remain fully compatible with existing aircraft systems while meeting the same quality standards as conventional jet fuel.

• • • Key Terms & Glossaries in Sustainable Aviation Fuel (SAF)
    • Empowering a Sustainable Future: Driving the Green Transition

Key Terms and Glossaries

• Clear and Bright: Fuel containing no visible water drops, particulates, haze, or cloudiness.
• Free water: Excess water beyond fuel solubility that appears as haze, cloudiness, droplets, or a water layer.
• Particulates: Small solid or semi-solid particles, sometimes referred to as silt or sediment, that may or may not be suspended in the fuel as a result of contamination by air-blown dust, corrosion by-products, fuel instability, or protective-coating deterioration.
• Closed-circuit Sampler: A container with inlet/outlet valves, a conical base, and a swirling fill port design. It may include a hydrometer and water detection ports.
• Appearance Photographs: Standard photos numbered 1-6 show increasing haze levels. Clear fuel rates are “one.”

Conclusion

Proper aviation fuel sampling is a cornerstone of flight safety, protecting lives and valuable aircraft assets. Through systematic sampling procedures, specialized equipment, and rigorous testing protocols, aviation professionals can detect and prevent fuel contamination before it becomes hazardous.

Understanding visual inspection techniques and advanced laboratory testing methods allows quick identification of common contaminants like water, particulates, and microbial growth. These procedures, backed by ASTM D1655 and DEF STAN 91-91 specifications, ensure consistent fuel quality across global operations.

Indeed, mastering these sampling procedures requires dedication and attention to detail. Yet this investment pays significant dividends – reducing contamination risks by up to 90% while maintaining the highest safety standards throughout the fuel handling chain.

Remember that adequate fuel sampling represents more than just a regulatory requirement. Instead, it serves as your first line of defense against potentially catastrophic fuel-related incidents, safeguarding both aircraft performance and passenger safety. Following these established procedures and staying current on evolving standards helps maintain the exceptional safety record that defines modern aviation.