Commercial and Business Aviation Advisory Circulars

Notice to Operators of Piper PA-31 Navajo Aircraft Operation in Icing Conditions

PURPOSE

Several operators of the PA-31 Navajo aircraft (including PA-31, PA-31-325 and PA-31-350) have expressed concern over the approval of their aircraft to operate in known icing conditions. The purpose of this Air Carrier Advisory Circular (ACAC) is to identify those aircraft eligible for flight into known icing.

BACKGROUND

This ACAC supersedes 0043 dated March 5, 1994.

Following the issue of ACAC 0043, several operators reported an apparent conflict between the ACAC and their Aircraft Flight Manuals (AFMs). In several cases, the AFM Limitations Section indicated that flight into light or moderate icing conditions was approved, although the aircraft serial number did not meet the eligibility criteria stated in the ACAC or Type Certificate.

Transport Canada Aviation (TCA) forwarded this anomaly to the FAA who, upon further investigation, revealed an inconsistency in the certification process used for the Navajo. Specifically, Piper referenced different certification criteria when determining whether an aircraft could fly in "light to moderate" versus "known" icing. "Known" icing includes only light to moderate conditions.

Since the Navajo is not certified to operate in severe icing conditions, TCA and the FAA have agreed to permit operation in light to moderate, known, forecast or reported icing for only the following models of Navajo aircraft:

1. any serial number where the aircraft was originally delivered, and the original AFM approved for flight in "light to moderate" or "known" icing conditions;
    
2. the following serial numbers, when equipped with optional ice protection equipment in accordance with the airplane equipment list:
    
   PA-31 and -31-325
          31-8012001 and up
    
   PA-31-350
          31-8052001 and up;
    
3. the following serial numbers, when modified in accordance with Piper Drawing 71983:
    
   PA-31-350
          31-7652124 through 31-7952250.

Aircraft that were delivered from the factory without ice protection equipment, and not bearing a serial number eligible to accept the option package or modification, may be similar in appearance to eligible models, but may not have adequate pneumatic capacity to provide suitable ice protection.

DECISION

Unless a PA-31 Navajo aircraft bears a serial number eligible to accept the ice protection modification as detailed by Piper, or was approved for flight in icing conditions when originally delivered from the factory, that aircraft is not approved for flight into known icing conditions, regardless of installed equipment.

Operators should verify that their aircraft meet the criteria for known icing conditions before engaging in this type of operation.

CONCLUSION

This revised ACAC has identified the Piper PA-31 Navajo aircraft eligible for flight into known icing conditions. Any enquiries concerning the contents of this ACAC should be directed to Air Carrier Operational Standards at (613) 990-1221 or by facsimile at (613) 954-1602.

A.J. LaFlamme
Director
Air Carrier