Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
AIR-21-19 R1
March 14, 2022
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) alerts owners,
operators, and maintenance personnel of an airworthiness concern on MD
Helicopters Inc. (MDHI) Model 369D, 369E, 369F, 369FF, 500N, and 600N
helicopters with Colorado Helicopters, Inc. Supplemental Type
Certificate (STC) SH5230NM Side Pull Hook Assembly installed. This is a
revision to AIR-21-19 SAIB.
At this time, the airworthiness concern is not an unsafe condition
warranting an airworthiness directive (AD) action under Title 14 of the
Code of Federal Regulations (14 CFR) part 39.
Background
The Federal Aviation Administration (FAA) became aware that the
breakaway pin installed in the breakaway swivel of the side pull hook
link installation could be replaced with the wrong pin or a bolt prior
to operations. The side pull hook link includes a breakaway swivel, a
calibrated breakaway pin, and a retaining ring (See Figure 1 below).
The side pull hook link installation is certified for a maximum pull
load of 1,900 pounds and is safeguarded by the calibrated breakaway pin
connecting the two pieces of the swivel. If the side pull hook link
installation is overloaded, the breakaway pin is designed to shear and
allow the load line to fall away without upsetting the helicopter.
Installation of other than the approved breakaway pin could result in
helicopter damage, upset, and even loss of control if the maximum pull
load of 1,900 pounds is exceeded. The swivel is installed in between
the hook link assembly, which attaches to the helicopter, and the line
attached to the load. The pin is 1.15 inch ±.003 inch long with
one end painted GREEN (not BLUE) and fills the hole through the swivel.
The pin has two smaller diameters allowing it to break in shear at a
specified load. It does NOT contain any threaded features and does not
protrude from the swivel. The pin is held in place with a steel
retaining ring installed in a groove around the circumference of the
swivel. If further verification is necessary, then FAA certified
maintenance personnel should disassemble the side pull hook link to
conduct a visual inspection. This inspection is a visual verification
of the shear diameters and lack of threads, and is accomplished by
removal of the steel ring and pin. Additionally, you may measure the
shear diameter (the smallest diameter of the pin in two places) to be
.149 inch +.000/-.003 inches, not larger.
Consequently, on November 29, 2021, the FAA issued SAIB AIR-21-19,
which included recommendations to address this concern. After the SAIB
was issued, the FAA became aware the SAIB recommendations contained
errors. The SAIB is revised accordingly.
Recommendations
The FAA recommends all owners/operators of the affected aircraft listed
in the introduction of this SAIB conduct a one-time inspection ensuring
FAA certified maintenance personnel remove the retaining ring,
breakaway pin, and inspect the breakaway pin for the correct color
(GREEN), appearance, and shear diameter prior to the next side pull
operation. If the pin matches the description above and has no signs of
damage, reinsert the pin and reinstall the retaining ring prior to
flight. If the pin does not match the description above, or shows signs
of damage, it should be replaced with pin part number 91106-018 prior
to the next side pull operation.
Additionally, the FAA continues to recommend all pilots of the affected
aircraft listed in the introduction of this SAIB visually inspect the
breakaway pin, per Figure 2, immediately before any side pull
operations. If the pin is not secured by the retaining ring, or is not
green on one end, or does not fill the hole through the swivel, or
shows signs of damage, it should be replaced with pin part number
91106-018 prior to the next side pull operation.
For Further Information Contact
Ronnea Derby, Aerospace Engineer, FAA, Denver ACO Branch, 26805 E 68th
Ave., Denver, CO 80249, United States; phone: (303) 342-1093; fax:
(303) 342-1088; e-mail: Ronnea.L.Derby@faa.gov.
