SAIB NM-20-12

1 FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Powerplant System – Operating in Icing Conditions SAIB: NM-20-12 Date: June 18, 2020 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) advises owners and operators of Yaborã Indústria Aeronáutica S.A. (Type Certificate Previously Held by Embraer S.A.) Model ERJ 170-100, ERJ 170-200, ERJ 190-100 and ERJ 190-200 airplanes of the potential for in-flight thrust loss when operating in weather conditions with high concentration of ice crystals.

At this time, the airworthiness concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) part 39.

Background

In the aviation industry, “icing conditions” is a well-known and documented phenomenon. It occurs with the presence of liquid water droplets in temperatures lower than the freezing point. Such environmental conditions can cause ice to adhere to the cold airframe. However, there is another phenomenon known as “ice crystal icing”, which is less common and harder to detect using radar returns. These conditions, which have shown high concentration of ice crystals, are found almost exclusively in the vicinity of deep convective clouds. Large convective formations have the capacity to lift high concentrations of moisture to high altitudes. When this moisture reaches low ambient temperature, it freezes into ice crystals. Thus, the potential to cause substantial effects to the airplane airframe and systems is higher in such conditions.

A result of this phenomenon is that the ice crystals, although in large concentration around the deep convective storm, are small in size. The onboard weather radar provides good awareness for rain, hail, and snow. When flying into ice crystals (even in high concentration), the radar only provides little or no reflectivity due to their size.

Several in-flight events on different airplane models from different manufacturers, are associated with this ice crystal phenomenon which has been identified as a serious potential environmental threat to turbine engines. Ice crystals melt when impinging on warm surfaces of the engine. The referred surfaces become wet and then cool to 0°C due to the impingement of additional ice crystals. As a result, ice begins to accumulate in some interior engine components and may cause loss of thrust.

In light of this data, Embraer issued Flight Operation Letter FOL N°: 170-006/18, Revision 01, “Ice Crystal Icing”, dated July 03, 2019 as Standard Operating Procedure (SOP), to inform operators of the procedure to avoid operation in weather conditions with a high concentration of ice crystals.

Recommendations

The FAA recommends that all owners and operators of the airplanes identified above incorporate the SOP outlined in the FOL at the earliest opportunity.

2 For Further Information Contact

Krista Greer, Aerospace Engineer, Large Aircraft Section, International Validation Branch, FAA, 2200 South 216th St., Des Moines, WA 98198; telephone and fax (206) 231-3221; e-mail [email protected].