NTSB Safety Alert SA-032 - Helicopter Safety Starts in the Hangar

Helicopter Safety Starts in the Hangar

Proper h elicopter maintenance is critical to flight safety

The problem

 Appropriate maintenance procedures and postmaintenance inspections are particularly

critical for helicopters because o f their mechanical and operational complexity and the

potentially adverse environments they operate in .

 A lack of v igilan ce in perform ing maintenance tasks or in verifying that the work was

done correctly can lead to accidents . One improperly torqued or degraded piece of

hardware may result in an uncontrollable helicopter.

 Fatigue and other human performance issues (such as stress, complace ncy, distraction,

pressure to complete work , and not adhering to standard operating procedures ) can

increase the risk of errors, even when performing the simplest tasks.

Related accidents

The NTSB has investigated several accidents in which maintenance personnel installed worn

hardware, performed inadequate installations, or omitted important maintenance steps .

 A pilot and four passengers died when a Eurocopter AS350B2 crashed in mountainous

terrain after the fore/aft control servo of the h elicopter disconnected during flight.

Maintenance errors identified during the investigation included the improper reuse of

hardware (degraded self -locking nuts) , the improper or lack of installation of a split pin,

and inadequate postmaintenance inspectio ns. Contributing to the errors were the

maintenance inspector’s fatigue and the lack of clearly delineated inspection steps.

(DCA12MA020 )

 A commercial pilot and two medical flight crewmembers died when a

Eurocopter AS350B3 descended rapidly and collided with terr ain following a loss of

engine power. The engine lost power because a fuel line fitting was improperly installed

during maintenance . Further, the postmaintenance inspection was inadequate , and the

postmaintenance check flight was too brief to comply with the manufacturer’s specified

checks. If the appropriate checks had been completed, the loss of engine power would

have likely occurr ed during the check flight . (WPR10FA371 )

 A student pilot sustained serious injuries during a solo cross -country flight when a

Schwei zer 296 C-1 lost engine power and collided with a building . Postaccident

examination found that the right magneto was installed incorrectly. Additionally,

maintenance personnel failed to ensure the correct magneto hardware was installed ,

thus missing an important step. (ERA09FA355 )

SA-032 February 2014, revised December 2015

What can mechanics do?

 Ensure that you receive adequate training so that you have the skills necessary to

complete specific maintenance task s.

 Use work cards , if available, to document completed maintenance steps. Doing so will

help ensur e the safety and security of items that have undergone maintenance and of

any surrounding components that may have been disconnected . If work cards are not

available, consider developing them from available maintenance manuals.

 Obtain independent inspections of critical items that have undergone maintenance.

 Verify that all work was performed in accordance with manufacturers’ procedure s and

work with flight check pilots to ensure that all appropriate checks are completed.

 Review available guidance and training materials regarding human performance errors

associated with aviation maintenance. These can include pressures to complete the

work, missed steps due to fatigue, and company procedures that are contrary to the

manufacturer’s guidance. Even experienced aviation maintenance technicians can

make mistakes.

Interested in more information?

The reports for the accidents referenced in this safety alert are accessible by NTSB accident

number from the NTSB’s Aviation Accident Database & Synopses web page at

www.ntsb.gov/aviationquery/index.aspx. Each accident’s public d ocket is accessible from the

NTSB’s Docket Management System web page at http://dms.ntsb.gov/pubdms/.

The Federal Aviation Administration (FAA) Safety Team ( FAASTeam ) provides access to

online training courses, seminars, and webinars. The courses Aircraft Maintenance

Documentation for AMTs , Dirty Dozen —Human Error in Aircraft Maintenance , Fatigue

Count ermeasure Training , and many others can be accessed from www.faasafety.gov .

The FAASTeam’s “GA Maintenance Alert: Safety and Security of Components ” provides an

overview of helicopter maintenance errors and suggestions for preventing similar errors and

can be accessed from www.faasafety.gov .

The International Helicopter Safety Team’s “Helicopter Maintenance Toolkit ” provides

guidance for safely maintaining helicopters and can be accessed from www.ihst.org .

The FAA’s Human Factors in Aviation Maintenance web page provides educational resources

for preventing human performance -related maintenance errors at

www.faa.gov/about/initiatives/maintenance_hf/ .

This NTSB safety alert and others can be accessed from the NTSB’s Safety Alerts web page

at http://www.ntsb.gov/safety/safety -alerts/Pages/default.aspx .