Type IV Aircraft Deicing/anti-icing Fluid DOW Chemical UCAR ENDURANCE EG106 Not Within Manufacturer’s Specification - Civil Aviation Safety Alert (CASA) No. 2023-01


All operators and de/anti-icing service providers

File Classification No.: Z 5000-35
RDIMS No.: 19284574
Document No.: CASA 2023-01
Issue No.: 02
Effective Date: 2023-02-24


Transport Canada (TC) was recently made aware that an aircraft deicing/anti-icing fluid (AAF) produced by DOW Chemical (DOW) was distributed throughout numerous stations within Canada and could have viscosity measurements higher than its specified maximum on-wing viscosity (MOWV).

This CASA serves as an awareness tool to all stakeholders with recommended measures to minimize safety risks for air operations in ground icing conditions.


DOW, an AAF manufacturer, recently advised TC that six (6) production batches of their (AAF) named UCAR ENDURANCE EG106 ADF/AAF (also known as EG106) had viscosity measurements that tested above its specified MOWV in the product information guidance (UCAR ENDURANCE EG106 Ethylene Glycol Type IV Aircraft Deicing/Anti-Icing Fluid).

The 6 production batches are:

  • D268MB8002 – Produced November 8, 2022
  • D268MBA000 – Produced November 11, 2022
  • D268MBM003 – Produced November 23, 2022
  • D268MC8000 – Produced December 8, 2022
  • D268M9K001 – Produced September 20, 2022*
  • D268N16000 – Produced January 6, 2023*

*Newly added

The shipments from the 6 production batches were delivered to the following stations:

The MOWV of EG106 is 47,800 mPa-s. However, DOW informed TC that the batch viscosities have ranged between 48,000 and 52,500 mPa-s.

DOW advised its customers of the product's inconsistency and provided a "No Technical Objection" (NTO) allowing its continued use.

Canadian Aviation Regulations (CARs) 602.11 – Aircraft Icing

TC implements the Canadian Aviation Regulations (CARs) 602.11 – Aircraft Icing which prescribes operator ground icing requirements, including those pertaining to the use of the Holdover Time (HOT) Guidelines through Standard 622.11 - Ground Icing Operations. There are no regulatory requirements for fluid manufacturers or service providers within the CARs.

Holdover Time Guidelines

The HOT Guidelines, developed and published annually by TC, are based on the Society of Automotive Engineers (SAE) Aerospace Recommended Practice (ARP)5718B - Qualifications Required for SAE Type II/III/IV Aircraft Deicing/Anti-Icing Fluid. The HOT Guidelines contain tables with time ranges for the use of many AAFs.

To fully utilize a holdover timetable, an AAF must have a viscosity that is above its lowest on-wing viscosity (LOWV) to achieve an adequate holdover time while also having a viscosity below the MOWV to ensure that the fluid can be used down to its lowest operational use temperature (LOUT).

Safety risks:

  1. The LOUT of EG106 may be impacted due to viscosities higher than its MOWV.

    The LOUT of this AAF was established as the warmer temperature of either:

    • The freezing point of the AAF + a 7°C buffer; or
    • The temperature resulting from the aerodynamic acceptance test (AAT) in AS5900, whichever is warmer.

    For EG106, this is the same temperature as its freezing point is -36°C and the AAT temperature is -29°C.

    The use of a fluid with a viscosity above its MOWV indicates that its LOUT has not been established. Therefore, operators may not be able to use EG106 down to the LOUT as identified in the HOT Guidelines.

    This is particularly important for smaller aircraft which typically take off at lower rotation speeds or have performance penalties applied when using AAF to ensure the aircraft can safely rotate.

  2. The aerodynamic acceptance methodology is unspecified.

    Although the NTO communicates that DOW has no concerns regarding fluid holdover time or aerodynamic acceptability, the aerodynamic acceptance testing methodology is not specified.

    The industry standard for establishing the aerodynamic acceptability of an AAF is the Aerospace Standard (AS) 5900 Standard Test Method for Aerodynamic Acceptance of AMS1424 and AMS1428 Aircraft Deicing/Anti-Icing Fluids.

    Until a correlation between the two test methods can be established or the AAF with a viscosity above the MOWV is verified by according to AS5900 to meet appropriate aerodynamic properties, there is no reliable data that would indicate the fluid is safe to use when its viscosity is above specification.

Recommended actions:

TC recommends the following:

  1. Operators should confirm with their service provider that the viscosity of EG106 is within acceptable viscosity limits.
  2. Operators should refrain from allowing the identified lots/batches of non-conforming DOW UCAR EG106 Type IV AAF to be applied because takeoff performance may be adversely affected.
  3. Purchasers or users of the identified batches of EG106 listed above confirm with DOW the fluid’s aerodynamic acceptance referenced in the NTO meets the requirements set out in AS5900
  4. Operators should confirm with their operations guidance (e.g., Flight Crew Operating Manual Cold Weather Supplementary Procedures, Ground Icing Operations Manual) and aircraft-related material (e.g., Aircraft Flight Manual, Aircraft Operating Manual, Safety Bulletins, Limitations) on the use of AAF above its MOWV. In the absence of supporting documentation, it is recommended that the operator contact the aircraft manufacturer.

Contact office:

For more information concerning this issue, contact a Transport Canada Centre; or contact Commercial Flight Standards in Ottawa by e-mail at AARTFinfo-InfoAARTF@tc.gc.ca.

Original signed by

Stacey Mason
Standards Branch


The Transport Canada Civil Aviation Safety Alert (CASA) is used to convey important safety information and contains recommended action items. The CASA strives to assist the aviation industry's efforts to provide a service with the highest possible degree of safety. The information contained herein is often critical and must be conveyed to the appropriate office in a timely manner. The CASA may be changed or amended should new information become available.