The Wall Street Journal
By ANDY PASZTOR
Updated Jan. 24, 2016 7:46 p.m. ET
European aviation regulators have ordered enhanced inspections and, if necessary, replacement of certain crack-prone parts on thousands of widely used AS 350 and other choppers manufactured by Airbus Group SE.
The aim is to prevent potentially dangerous structural failures related to main gearbox covers or their attachments, and “consequent loss of the helicopter.”
Safety mandates issued Friday by the European Aviation Safety Agency cover main gearbox casings and related parts on certain versions of AS 350 helicopters, which are popular for law enforcement, air-ambulance services and commercial operations. Industry officials said the four directives are expected to ultimately affect more than 3,000 Airbus rotorcraft world-wide, including about 1,000 registered in the U.S., once regulators from other countries embrace the agency’s move.
EASA’s documents don’t call for emergency fixes, and they complete safety moves the agency first proposed last summer. Airbus Helicopters previously issued a number of its own service bulletins dealing with the same issues.
European regulators are requiring stepped-up inspections—as frequently as every 10 flight hours for some older helicopters—to detect oil leaks that could be a sign of hazardous fractures.
The directives become effective early next month, and technically apply only to European-registered helicopters. Based on past practice and U.S.-European cooperative agreements, however, the Federal Aviation Administration is expected to follow-up with similar directives covering fleets in the U.S.
On Sunday, an Federal Aviation Administration spokeswoman said the agency “will evaluate and determine if an unsafe condition exists” before deciding whether to issue its own safety directive.
Single-engine AS 350s were first delivered in the 1970s, but since then various new versions have been introduced. Friday’s mandate also covers twin-engine variants, including some AS 355 models that are no longer in production.
EASA didn’t list any accidents or incidents stemming from such problems, but each of the directives stressed that structural analyses uncovered potential cracking of the main gearbox housing or an attachment point.
Airbus and EASA have said that certification of the latest AS 350 version revealed some “critical areas which had not been identified” during safety studies and testing of earlier versions.
Results of the latest inspections by operators are required to be submitted to company experts. In one of its service bulletins, the manufacturer said it has revised stress calculations for the affected parts, resulting in new limits for “the service life of these casings.”
Last October, the Federal Aviation Administration issued an unrelated emergency airworthiness directive covering the latest AS 350 models. The agency mandated changes in certain pilot ground-test procedures to prevent inadvertent jamming of some tail-rotor controls. The FAA acted after two accidents and one incident, and it said the manufacturer was developing a permanent fix.
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