In-flight monitoring of composite structural components such as helicopter rotor blades

• US 4,524,620 A
• Filed: 02/07/1983
• Issued: 06/25/1985
• Est. Priority Date: 02/07/1983
• Status: Expired due to Term

• Current Assignee: McDonnell Douglas Helicopter Co. (The Boeing Co.)
• Original Assignee: Hughes Helicopters Incorporated (The Boeing Co.)
• Inventors: Wright, Dale M., Kiraly, Robert L.
• Primary Examiner(s): Myracle, Jerry W.
• Assistant Examiner(s): Chapman, Jr., John E.
• Application Number:
  US06/464,343
• Time in Patent Office: 869 Days
• Field of Search: 73/583, 73/587, 73/801, 73/802, 416/61, 340/679, 340/683, 364/508
• US Class Current: 73/587
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00

Abstract

The apparatus comprises one or more acoustical transducers associated with a particular interchangeable rotor blade for monitoring acoustic emissions emitted by the rotor blade under operating stress. The output of the transducers is connected to a computer associated with the particular aircraft. The transducer output signals are processed by the computer and filtered to allow real time stress return level readings so as to accumulate a count of critical acoustic emissions which are indicative of progressive irreversible structural fatigue or damage to the interchangeable rotor blade.

Claims

1. Apparatus for determining the actual useful life of interchangeable helicopter blades comprising:

means associated with a particular helicopter rotor blade for monitoring acoustic emissions emitted by said rotor blade under operating stress;

computer means associated with said helicopter for accumulating a count of monitored acoustic emissions indicative of progressive structural failure of said interchangeable helicopter rotor blade, said computer means including data storage means for storing said count of acoustic emissions, and input means for entering a base count indicative of acoustic emissions emitted by said rotor blade during use prior to installation in said particular helicopter; and

indicator means for warning the crew of said helicopter of a cumulative count and/or stress level approaching a predetermined acoustic emission count associated with catastrophic failure of similar rotor blades such that the actual useful life of said rotor blade may be exhausted prior to actual rotor blade failure.

2. The apparatus of claim 1 wherein said mounting means comprise transducer means mounted to said rotor blade, and

detachable electrical connector means for interconnecting said transducer means to said computer.

3. Apparatus for determining the actual useful life of interchangeable helicopter blades comprising:

one or more transducers mounted to a particular interchangeable rotor blade for generating an electrical output responsive to acoustic emissions of said rotor blade;

computer means associated with a particular helicopter for accumulating a count of acoustic emissions indicative of progressive structural failure of said rotor blade;

input means for entering a base count indicative of acoustic emissions emitted by said rotor blade during use prior to installation in said particular helicopter;

detachable electrical connector means interconnecting said transducer means to said computer means; and

indicator means associated with said particular helicopter for indicating to the crew of said helicopter a continuously updated cumulative count of acoustical emissions in relation to a predetermined acoustic emissions count associated with imminent catastrophic structural failure of said rotor blade.

4. Method for measuring the actual remaining useful life of interchangeable helicopter rotor blades comprising:

installing a particular rotor blade on a first helicopter;

detecting acoustic emissions emitted by said rotor blade under operating stress indicative of progressive structural failure of said rotor blade;

accumulating a count of said acoustic emissions;

storing said count in a memory associated with said first helicopter;

removing said rotor blade;

installing said rotor blade on a second helicopter;

entering said stored count in a memory associated with said second helicopter;

detecting further acoustic emissions emitted by said rotor blade under operating stress indicative of continued progressive structural failure of said rotor blade;

adding said detected further emissions to said stored count; and

displaying said stored count for viewing by crew members of said second helicopter whereby the crew of said second helicopter may be forwarned prior to accumulating an acoustic emission count associated with imminent catastrophic structural failure of said rotor blade.