Appendix C C-2 engagement and deflect the primary engaging ring safely back into the throat of the hook, thus preventing D-ring reversal (see Figures C-3, Hook with a Mechanical Lock Latch Gate Design, and C-4, Hook with a Simple Spring-Loaded Safety Latch or Keeper).
Figure C-2. MS 18027-2A Hook MS 18027-2A Hook with simple spring-loaded safety catches. Note the exposed hook tips.
Figure C-3. Hook with a Mechanical Lock Latch Gate Design One type of hook which incorporates a mechanical lock latch gate design. The keeper also guards the tip of the hook.
Appendix C C-3 Figure C-4. Hook with a Simple Spring-Loaded Safety Latch or Keeper H ook used in a popular winch system which uses a simple spring-loaded safety latch or keeper.
C.2 Recommend Action.
1. Develop procedures which list the specific D-rings or equipment which may be attached to a specific rescue hook wherein the possibility of D-ring reversal is physically impossible.
2. Use only rescue hooks which have a mechanical locking keeper or guards to prevent ring reversal or dynamic rollout.
3. Ensure winch operational training is tailored for each helicopter type and winch combination and is completed on a regular basis.
4. Operate and maintain winches, hooks, and harnesses in accordance with approved data.
Advisory Circular Feedback Form If you find an error in this AC, have recommendations for improving it, or have suggestions for new items/subjects to be added, you may let us know by contacting the General Aviation and Commercial Division (AFS-800) at 9-AFS-800-Correspondence@faa.gov or the Flight Standards Directives Management Officer at 9-AWA-AFB-120-Directives@faa.gov.
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