AD2020-18-51 Prompted By A Report Of Three Failed Attitude Indicators

Emergency Airworthiness Directive (AD) 2020-18-51 is sent to owners and operators of various aircraft with Sandia attitude indicator (attitude indicator) part number (P/N) 306171-10 or 306171-20 installed. These attitude indicators may be marked as BendixKing Model KI-300 or Sandia Model SAI-340A.

This emergency AD was prompted by a report of three failed attitude indicator P/N 306171-10 units. Following the initial report, investigation has revealed a total of 54 failed attitude indicator P/N 306171-10 units. Attitude indicator P/N 306171-20 is affected by the same unsafe condition because it is identical to P/N 306171-10. The effect of the failure was erroneous attitude data provided to the pilot and autopilot, if equipped. In some instances, the pilot is unaware that the data is erroneous or unreliable. In other instances, where the aircraft is equipped with multiple displays, the pilot may be provided with conflicting information, but will have no way to determine which display contains the correct data. This condition, if not addressed, could result in aeronautical decision-making based on erroneous attitude information, which may result in loss of control of the aircraft.

The FAA is issuing this AD after evaluating all the relevant information and determining the unsafe condition described previously is likely to exist or develop in other products of these same type designs.

Emergency AD Requirements: This emergency AD requires, before further flight, revising the existing Airplane Flight
Manual (AFM) for your airplane to prohibit operation under Instrument Flight Rules (IFR) or night Visual Flight Rules (VFR) and prohibit coupling the autopilot with an affected attitude indicator. Revising the existing AFM for your airplane may be performed by the owner/operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft records showing compliance with this AD in accordance with 14 CFR 43.9(a)(1) through (4) and 14 CFR 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417. This authority is not applicable to aircraft being operated under 14 CFR part 119.

FMI: www.regulations.gov