Engine companies bidding for Boeing’s potential New Mid-sized Airplane (NMA) could face a new safety requirement proposed by regulators in response to a 2009 bird strike incident that caused an Airbus A320 to make an emergency landing in the Hudson River.
The US Federal Aviation Administration (FAA) proposed the new certification test in a notice published on 6 July. It follows a similar rule making proposed by the European Aviation Safety Agency (EASA) last year.
Both agencies launched the lengthy rulemaking process based on a recommendation by the US National Transportation Safety Board (NTSB), which had investigated the 15 January 2009 bird strike incident on US Airways Flight 1549.
Both of the A320’s engines ingested multiple Canada geese at about 2,800ft and 230kt during a climb-out from New York LaGuardia Airport. Despite losing nearly all engine thrust due to damage caused by the birds entering the engine core, pilot Chesley “Sully” Sullenberger successfully landed the A320 in the Hudson River. All 150 passengers and crew aboard survived.
Although Sullenberger’s landing was successful, the near-disaster shook the confidence of regulators. Certification rules now require a bird ingestion test, but only during a full power take-off with the fan blades rotating at maximum speed.
Such a rule covers the risky scenario of an engine shutdown on takeoff caused by a bird ingestion, but does nothing to guarantee the safety of an engine during climb-out and descent. Pilots usually pull back the throttles shortly after taking off and run the engines back to idle on descent, so the fan blades are rotating more slowly than at full power. As the fan blades slow down, the concern is that larger pieces of the bird could enter the core of the engine.
So both regulators are proposing to amend the certification test requirements. Engine designs that have already applied for or received a certification, including the GE Aviation GE9X, would be grandfathered under the old rule. But new engine designs that apply for a type certification with the FAA or EASA could be subject to the proposed amended standard.
The FAA’s criteria matches the EASA’s proposed rulemaking from last year.
The new standard would require an ingestion test that simulates a medium-sized bird entering an engine core at 250kt at an altitude of 3,000ft, the FAA document dated 6 July states. The engine must be able to produce at least 50% of maximum rated thrust for up to 1min after the ingestion.
EASA and FAA have also proposed another test, but only if engine makers determine by analysis or test result that no part of the bird would enter the core at 250kt. The second test would require an engine to ingest a bird at 200kt at a simulated altitude of 3,000ft, with the fan rotating at the slowest possible speed.
The FAA will accept comments about the proposed rulemaking until 4 September. The comment period for the EASA rule closed last fall, but a final rule has not yet been publsihed.
Source: FlightGlobal.com
