Navigation: Water freezing in Pitot-Static System

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FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SAIB: CE-12-05 SUBJ: Navigation: Water freezing in Pitot-Static System Date: November 2, 2011 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) is to inform the owners and operators of Piaggio Aero Industries S.p.A. (Piaggio) P-180 airplanes, manufacturers serial numbers 1105 through 1213 and 1218, of an airworthiness concern, specifically water freezing in the pitot-static system in flight resulting in dual air data computer (ADC) failures.

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

Background

There have been numerous cases of in-service events that have been reported involving airspeed mismatch between the pilot and co-pilot’s airspeed indications and, in four cases, loss of ADC airspeed information. The cause was determined to be from water being accumulated and trapped in the air data system lines, which froze at high altitude causing the blockage of pitot system lines with ice. This situation, if not corrected, could lead to further cases of erroneous airspeed indications or single/dual ADC failures.

As a corrective action and to avoid any problem of moisture accumulation and consequent icing in the pitot lines, Piaggio developed a modification of the pitot-static system routing that provides better draining efficiency. This modification was approved by EASA, and Piaggio has issued their Service Bulletin (Mandatory) No. 80-0326, Rev. 0, dated July 4, 2011.

The Federal Aviation Administration issued an airworthiness concern sheet (ACS) in September 2010, to operators to determine if any other events, similar to the two cited events listed above, have occurred. None were reported nor did the FAA receive any additional adverse service history from the U.S. operators.

Recommendation

The FAA recommends you comply with the above-referenced service bulletin within 1,500 flight hours (FH), or within 2 years (whichever occurs first) from the issue date of this service bulletin. Piaggio recommends the service bulletin be accomplishment during a “C” or “D” aircraft inspection, or when the forward bulkhead inspection for cracks and corrosion is performed.

For Further Information Contact

Mike Kiesov, Aerospace Engineer, FAA Small Airplane Directorate, Room 301, 901 Locust, Kansas City, Missouri 64106; phone: (816) 329-4144; fax: (816) 329-4090; email: [email protected].

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For Related Service Information Contact

Piaggio Aero Industries, Via Cibrario, 4, 16154, Genoa, Italy, e-mail: [email protected].