While cruising at 150 kt at 750 ft agl on 5th July 2011 after departing Battersea Heliport, the aircraft (an Agusta 109C registration N109TK) struck a bird which shattered the left windshield. The commander, seated in the left seat, suffered minor injuries so the co-pilot took control and made a successful emergency landing near Kew Bridge in West London. The Agusta A109C’s windshield is not designed to withstand bird strikes and the regulations do not require it to do so. The US National Transportation Safety Board has recommended to the US Federal Aviation Administration that the regulations covering helicopters of the Agusta A109C’s category should require a bird strike resistant windshield.
The 109C post gull strike
The Press Association: Gull forced helicopter to land
Incident Report
Some tidbits from the report:
The bird, which was mostly intact, was found inside the helicopter and was identified as a Herring Gull. The bird was not sent for analysis but the typical weight of a Herring Gull is 690 to 1,495 g and the species is classified as ‘High’ on the Hazard Probability list.
Previous incidents of A109 bird strikesThe aircraft manufacturer was aware of three previous birdstrike incidents involving the A109 type. One of these (A109E, registration N911UF) occurred on 3 May 2009 in Florida, USA and was investigated by the US National Transportation Safety Board (NTSB). The NTSB reported that while descending at 145 kt through 800 feet the windshield ‘exploded’ and the pilot was ‘pelted’ with pieces of windshield and other debris.
A further birdstrike incident occurred to an A109E in Mexico in November 2009 and resulted in most of the right windscreen being destroyed. The unidentifiedbird came to rest to the right of the right rear passenger seat. The pilot suffered minor injuries but was able to land safely.
Several circuit breakers and switches were broken off and some switches had moved to the off position. The pilot landed the aircraft safely and post-flight examination revealed that a 1 to 1.5 kg duck had come to rest inside the cabin. The NTSB report also noted that:
‘The master caution warning light started flashing, but the pilot had difficulty reading the caution warning lights as the left lens to his eyeglasses was missing. The pilot was eventually able to determine that SAS2 number 1 had been disengaged, and after resetting the switches, the master caution light extinguished.’
‘there was no forward shielding of the overhead panel switches and
throttles.’
Responding to the earlier 109 incidents the NTSB made the following safety recommendation to the FAA:
‘Revise 14 Code of Federal Regulations Part 27 to specify a bird weight and velocity of impact that the helicopter must withstand and still be able to and safely and that the windshield must withstand without penetration. Consider current military and civilian bird-strike database information and trends in bird populations in drafting this revision.
The FAA responded to this recommendation in January 2011 by stating that they are reviewing multiple bird-strike databases to determine whether Part 27 should be included in the rotorcraft regulatory and policy review, and that an updated response would be provided in December 2011.