Move Follows Fatal Accident In Southern Indiana

The FAA has published an Airworthiness Directive (AD) that grounds all Cessna Models 525, 525A, and 525B airplanes with Tamarack active load alleviation system (ATLAS) winglets installed in accordance with Supplemental Type Certificate (STC) SA03842NY. The AD results from mandatory continuing airworthiness information (MCAI) issued by the aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as malfunction of the ATLAS.

The MCAI states that The active load alleviation system (ATLAS), when operational, deflects the Tamarack active control surfaces (TACS) on the outboard wings. Recently, occurrences have been reported in which ATLAS appears to have malfunctioned, causing upset events where, in some cases, the pilots had difficulty to recover the airplane to safe flight. Investigation continues to determine the cause(s) for the reported events.

This condition, if not corrected, could lead to loss of control of the airplane. To address this potential unsafe condition, Cranfield Aerospace Solutions have issued the [service bulletin] SB, providing instructions to pull and collar the ATLAS circuit breaker, to make TACS immovable and to amend the applicable AFMS.

For the reasons described above, this [EASA] AD requires the Tamarack ATLAS to be deactivated and the TACS to be fixed in place. This [EASA] AD also requires implementation of operational limitations and repetitive pre-flight inspections by amending the applicable AFMS. Finally, this [EASA] AD requires a modification of the ATLAS, which would provide relief for the deactivation, limitations and repetitive inspections as required by this AD.

This [EASA] AD is an interim action and further AD action may follow. The National Transportation Safety Board (NTSB) is investigating a fatal accident involving a Model 525 airplane with the ATLAS STC installed. The NTSB investigation focuses on the role the ATLAS may have played in the accident. In addition to the accident, five incidents of aircraft uncommanded roll events with the ATLAS activated have been reported to EASA and the FAA. In each incident, the pilot was able to recover from the event and land the aircraft safely.

The FAA indicates in the AD that product has been approved by the aviation authority of another country, and is approved for operation in the United States. Pursuant to our bilateral agreement with this State of Design Authority, they have notified us of the unsafe condition described in the MCAI and service information referenced above. The agency is issuing this AD because we evaluated all information provided by the State of Design Authority and determined the unsafe condition exists and is likely to exist or develop on other products of the same type design.

The EASA AD allows operation for up to 100 flight hours with the system disabled and with the same operating limitations as in the MMEL. However, this AD does not allow operation with the ATLAS disabled. Instead, this AD prohibits all flight until a modification has been incorporated in accordance with an FAA-approved method. Until a modification method is developed and approved, this AD requires revising the operating limitations in the AFM and fabricating and installing a placard to prohibit further flight.

The FAA finds the service information from the STC holder (Cranfield Aerospace Solutions) does not contain adequate instructions to safely disable the ATLAS. Those instructions include the use of “speed tape” around each Tamarack active camber surface (TACS) to keep them faired in the neutral position during flight. Any modifications mandated through AD action become changes to the type design in the U.S. system. The FAA would need to ensure that the use of speed tape complies with the applicable airworthiness regulations for use on a movable surface to hold that surface in a fixed position. The speed tape does not have sufficient testing and analysis to support the type design change. This program would involve testing for environmental effects, fatigue analysis, and analysis of hazards due to potential failures of the tape. Without more analysis, the security of the speed tape method to prevent movement of the TACS cannot be assured, and loss of control of the airplane may occur with the ATLAS disabled. An operator or Cranfield may provide substantiating data to the FAA and request an alternative method of compliance using the procedures in this AD.

This AD specifies that the owner/operator (pilot) may revise the AFM and may fabricate and install a placard prohibiting flight. Revising an AFM is not considered a maintenance action and may be done by a pilot holding at least a private pilot certificate. Allowing the pilot to fabricate and install a placard is an exception to our standard maintenance regulations. These actions must be recorded in the aircraft maintenance records to show compliance with this AD.

The FAA estimates that this AD affects 76 products of U.S. registry. It further estimates that it will take about 2 work-hours per product to revise the Operating Limitations section of the AFM and to fabricate and install a placard. The average labor rate is $85 per work-hour. We estimate the parts cost to fabricate the placard as $5.

Based on these figures, the estimated cost of the proposed AD on U.S. operators to is $175 per product.

The AD prohibits flight until the incorporation of an FAA-approved modification. At this time, a modification does not exist; therefore, we have no data to use for estimating the cost of the modification.

The AD is effective immediately. The comment period is open through July 8th.

(Images from file)

FMI: AD