11-Apr-2013 Source: NZ CAA
The CAA proposes the following new Airworthiness Directive requiring the replacement of aluminium fuel tanks on Robinson R44 series aircraft with new bladder-type tanks of improved resistance to post-accident rupture.
The AD is prompted by reports of three Robinson R44 accidents in Australia involving fuel tank ruptures and fires. These accidents resulted in the loss of eight lives due to fatal injuries sustained in post-impact fire.
Further information about these accidents can be obtained from the ATSB Preliminary Report AO-2013-055, dated 5 April 2013 which is available on the ATSB web site at http://www.atsb.gov.au/publications/safety-investigation-reports.aspx?mode=Aviation The bladder tanks introduced by Robinson Helicopter Company R44 SB-78 have been certified to meet the latest crash resistance requirements of FAR §27.952. Specifically, this requires the fuel tanks to be able to sustain a drop-test when 80% full from a height of 50 feet without any fuel leaks. This requirement was introduced in 1994 by the FAA, which summarized the issue at the time of the Final Rule:
“Post-crash fires (PCF’s) are the primary cause of fatalities and injuries in otherwise survivable impacts resulting from rotorcraft accidents. It is estimated that 5 percent of the occupants in survivable rotorcraft accidents are killed or injured by PCF’s annually. These types of fatalities and traumatic injuries will be substantially reduced by the implementation of the design and test criteria of this amendment. Nearly all PCF’s are caused by crashinduced fuel leaks that quickly come in contact with ignition sources during or after impact.
The fuel containment and hazard elimination provisions contained in this amendment will, in the majority of cases, give occupants the time necessary to escape a survivable crash before a post-crash fire (PCF) could become life threatening. A crash resistant fuel system (CRFS) would not be expected to prevent all fires; however, a CRFS would, in the majority of survivable accidents, either prevent a PCF or delay the massive fire, or fireball, long enough to allow the occupants to escape. These standards have been validated by military safety statistics as significantly minimizing the PCF hazard and its associated fatalities and injuries.”
You can read the full text of the Final Rule at: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/9A1468ACA18ABDEB862579C7005C47F8?OpenDocument
Written submissions regarding the following proposed new Airworthiness Directive are invited. The closing date for submissions is 15 May 2013.
Please send your submissions to the CAA at firstname.lastname@example.org
Dated 11 April 2013
DCA/R44/XX Bladder Fuel Tank – Retrofit
Applicability: Robinson R44 and R44 II helicopters not fitted with bladder fuel tanks.
Note: Robinson Helicopter Company R44 Service Bulletin SB-78B dated 28 September 2012 introduces bladder tank retrofit kits KI-196-1 and KI-196-2 for R44 series helicopters.
Requirement: To improve the fuel tanks resistance to post-accident rupture and fuel leaks which could result in a non-survivable fire, accomplish the following:
Replace the aluminium fuel tanks with bladder-type tanks in accordance with Robinson Helicopter Company R44 SB-78B dated 28 September 2012, or later FAA approved revisions.
Compliance: Within next 6 months
Effective Date: XX/XX/XXXX