Lightning
I operate from EGSH.
In July 2002, 11 people lost their lives in a Helicopter operating from this base, this event was attributed somewhat to lightning.
The rather short AAIB report can be found here.
http://www.aaib.gov.uk/cms_resources.cfm?file=/dft_avsafety_pdf_503164.pdf
This aircraft was fully lightning certified, inspected and approved to all of the required standards. After the lightning strike the blade in question underwent further inspection by the manufacturers.
There is an increased appreciation of the effects of lightning, at this airfield at least!
This rotor blade was manufactured in March 1981. In 1999 when fitted to Sikorsky S76A G-BHBF
it was damaged by a lightning strike (see AAIB Bulletin 3/2001). At that time the blade had
accumulated 8,261 hours usage. The blade was returned to the manufacturer for assessment where,
following inspection, it was repaired and returned to service. Neither the thermal damage to the
spar nor the manufacturing anomaly were detected during this inspection. At the time of the
accident, the blade had accumulated 9,661 hours usage. The airworthiness limitation life of the
blade is 28,000 hours.
The AAIB and the helicopter's manufacturer are of the opinion that the electrical energy imparted
by the lightning strike in 1999 exploited the anomaly that was built into the blade at manufacture
and damaged the spar.
Safety action
On 24 July the aircraft manufacturer issued Alert Service Bulletin (ASB) 76-65-55. The purpose of
this ASB was "To remove from service any main rotor blade identified as having been damaged by
a lightning strike". A modified version of the ASB (76-65-55A) was issued the next day. The
modifications related to the accomplishment instructions and did not alter the purpose of the
original ASB. The modified ASB was subsequently mandated by Emergency Airworthiness
Directive 2002--15-51 issued on 26 July by the Federal Aviation Administration.
Nature, the only “Superpower” can be a formidable adversary.
Take care.
Charlie.