[Federal Register Volume 60, Number 41 (Thursday, March 2, 1995)]
[Rules and Regulations]
[Pages 11611-11613]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-5096]
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Rules and Regulations
Federal Register
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Federal Register / Vol. 60, No. 41 / Thursday, March 2, 1995 / Rules
and Regulations
[[Page 11611]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-SW-12-AD; Amendment 39-9165; AD 95-04-13]
Airworthiness Directives; Robinson Helicopter Company Model R44
Helicopters
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment supersedes an existing airworthiness directive
(AD), applicable to Robinson Helicopter Company Model R44 helicopters,
that currently requires revisions to the Limitations section, the
Normal Procedures section, and the Emergency Procedures section of the
R44 Rotorcraft Flight Manual, revised September 6, 1994. These
revisions limit operations in high winds and turbulence; provide
information about main rotor (M/R) stalls and mast bumping; and provide
recommendations for avoiding these situations. Additionally, emergency
procedures are provided for use should certain conditions be
encountered. This amendment requires the same revisions required by the
existing Priority Letter AD, but revises certain words and phrases to
further clarify the revised Limitations and Normal Procedures sections,
deletes the paragraph that referenced recording compliance with the AD,
and adds another paragraph that states that no special flight permits
will be issued prior to compliance with this AD. This amendment is
prompted by two Model R44 accidents since April 1994 involving M/R
blades contacting the helicopters' fuselage; and, 26 accidents
involving M/R blades contacting the fuselage on the Model R22
helicopter since 1981. The Model R22 helicopter M/R system design is
similar to the Model R44 helicopter M/R system design. The actions
specified by this AD are intended to prevent M/R stall or mast bumping,
which could result in the M/R blades contacting the fuselage causing
failure of the M/R system and subsequent loss of control of the
helicopter.
DATES: Effective March 17, 1995.
Comments for inclusion in the Rules Docket must be received on or
before May 1, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Office of the Assistant Chief Counsel, Attention:
Rules Docket No. 95-SW-12-AD, 2601 Meacham Blvd., Room 663, Fort Worth,
Texas 76137.
FOR FURTHER INFORMATION CONTACT: Mr. Scott Horn, Aerospace Engineer,
FAA, Rotorcraft Directorate, Rotorcraft Standards Staff, Southwest
Region, 2601 Meacham Blvd., Fort Worth, Texas 76137, telephone (817)
222-5125, fax (817) 222-5961.
SUPPLEMENTARY INFORMATION: On January 12, 1995, the FAA issued Priority
Letter AD 95-02-04, to require revisions to the Limitations section,
the Normal Procedures section, and the Emergency Procedures section of
the R44 Rotorcraft Flight Manual, revised September 6, 1994. These
revisions limit operations in high winds, turbulence, and wind shear
conditions; provide information about M/R stalls and mast bumping; and,
provide recommendations for avoiding these situations. That action was
prompted by two Model R44 accidents since April 1994 involving M/R
blades contacting the helicopters' fuselage. M/R stall and mast bumping
may have caused these M/R blade contacts with the fuselage. Both of
these accidents resulted in fatalities. Limited pilot experience in
rotorcraft has been identified as common to these accidents. High winds
and turbulence were also noted in both of the accidents. Airspeed and
low rotor RPM could also be influencing factors in these M/R blades
contacting the fuselage. Flight in strong or gusty winds, areas of wind
shear, or areas of moderate, severe, or extreme turbulence can degrade
the helicopter handling qualities, thereby creating an unsafe
condition. These conditions, if not compensated for, could result in M/
R stall or mast bumping, which could result in the M/R blades
contacting the fuselage causing failure of the M/R system and
subsequent loss of control of the helicopter.
Since the issuance of that AD, the FAA has determined that the
words ``areas of forecasted or reported'' should be deleted from the
revision to the Limitations section of the Model R44 Rotorcraft Flight
Manual, revised September 6, 1994. Some operators receive area
forecasts and reports that cover wide geographic regions. These
forecasts and reports can refer to turbulence in areas unrelated to the
actual area of operation. Forecasted or reported wind shear or
turbulence outside of the operational area was not intended to be a
flight limitation. The word ``spreads'' was added to the term ``wind
gusts'' to define this limitation as the spread or variance of wind
velocities. The phrase ``but no lower than 60 knots'' was added to the
Limitations section because of the possibility that at higher
altitudes, 0.7 Vne could be lower than 60 knots. Additionally, the
phrase ``but no lower than 60 knots'' was added to recommendation (1)
of the Normal Procedures section because of the possibility that at
higher altitudes, 0.9 Vne could be lower than 60 knots. Below 60
knots, the energy required to recover from a low-rotor RPM condition by
flaring the helicopter and converting forward airspeed to rotor speed
is unavailable. The reference to the requirement to report compliance
that was contained in paragraph (b) of the existing Priority Letter AD
has been deleted since part 91.147(a)(2)(v) already contains that
requirement. Finally, another paragraph has been inserted to state that
special flight permits will not be issued to operators for the purpose
of obtaining and inserting the three pages into the rotorcraft flight
manual. Due to the immediate compliance time and the criticality of
preventing M/R blade contacts with the fuselage, this rule is being
issued immediately to revise the operating limitation of the helicopter
to a safer level.
Since an unsafe condition has been identified that is likely to
exist or develop on other Robinson Helicopter Company Model R44
helicopters of the same type design, this AD supersedes Priority Letter
AD 95-02-04 to require the same revisions to the Limitations
[[Page 11612]] section, the Normal Procedures section, and the
Emergency Procedures section of the R44 Rotorcraft Flight Manual,
revised September 6, 1994, that were required by the Priority Letter
AD, but deletes the words ``areas of forecasted or reported'' from the
wind turbulence limitation; adds the word ``spreads'' when referencing
wind gusts; adds the phrase ``but no lower than 60 knots'' to the same
section; deletes the reference to the requirement to record compliance
that was contained in paragraph (b) of the existing Priority Letter AD;
and, adds another paragraph to state that special flight permits will
not be issued to accomplish the requirements of this AD.
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this rule by
submitting such written data, views, or arguments as they may desire.
Communications should identify the Rules Docket number and be submitted
in triplicate to the address specified under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the rule. All comments submitted will be
available, both before and after the closing date for comments, in the
Rules Docket for examination by interested persons. A report that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket No. 95-SW-12-AD.'' The postcard will be date stamped and
returned to the commenter.
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, may be obtained from the Rules Docket at the
location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive
(AD), Amendment 39-9165, to read as follows:
95-04-13 Robinson Helicopter Company: Amendment 39-9165. Docket No.
95-SW-12-AD. Supersedes Priority Letter AD 95-02-04, issued January
12, 1995.
Applicability: Model R44 helicopters, certificated in any
category.
Compliance: Required before further flight, unless accomplished
previously.
To prevent main rotor (M/R) stall or mast bumping, which could
result in the M/R blades contacting the fuselage causing failure of
the M/R system and subsequent loss of control of the helicopter,
accomplish the following:
(a) Insert the following information into the Model R44
Rotorcraft Flight Manual, revised September 6, 1994. Compliance with
the Limitations section is mandatory. The Normal Procedures and
Emergency Procedures sections are informational.
Limitations Section
(1) Flight when surface winds exceed 25 knots, including gusts,
is prohibited.
(2) Flight when surface wind gust spreads exceed 15 knots is
prohibited.
(3) Flight in wind shear is prohibited.
(4) Flight in moderate, severe, or extreme turbulence is
prohibited.
(5) Adjust forward airspeed to between 60 knots and 0.7 Vne
but no lower than 60 knots upon inadvertently encountering moderate,
severe, or extreme turbulence.
Note: Moderate turbulence is turbulence that causes: (1) Changes
in altitude or attitude; (2) variations in indicated airspeed; and
(3) aircraft occupants to feel definite strains against seat belts.
Normal Procedures Section
Note
Until the FAA completes its research into the conditions and
aircraft characteristics that lead to main rotor blade/fuselage
contact accidents, and corrective type design changes and operating
limitations are identified, R44 pilots are strongly urged to become
familiar with the following information and comply with these
recommended procedures.
Main Rotor Stall: Many factors may contribute to main rotor
stall and pilots should be familiar with them. Any flight condition
that creates excessive angle of attack on the main rotor blades can
produce a stall. Low main rotor RPM, aggressive maneuvering, high
collective angle (often the result of high-density altitude, over-
pitching [exceeding power available] during climb, or high forward
airspeed) and slow response to the low main rotor RPM warning horn
and light may result in main rotor stall. The effect of these
conditions can be amplified in turbulence. Main rotor stall can
ultimately result in contact between the main rotor and airframe.
Additional information on main rotor stall is provided in the
Robinson Helicopter Company Safety Notices SN-10, SN-15, SN-20, SN-
24, SN-27, and SN-29.
Mast Bumping: Mast bumping may occur with a teetering rotor
system when excessive main rotor flapping results from low ``G''
(load factor below 1.0) or abrupt control input. A low ``G'' flight
condition can result from an abrupt cyclic pushover in forward
flight. High forward airspeed, turbulence, and excessive sideslip
can accentuate the adverse effects of these control movements. The
excessive flapping results in the main rotor hub assembly striking
the main rotor mast with subsequent main rotor system separation
from the helicopter.
To avoid these conditions, pilots are strongly urged to follow
these recommendations: [[Page 11613]]
(1) Maintain cruise airspeeds greater than 60 knots indicated
airspeed and less than 0.9 Vne, but no lower than 60 knots.
(2) The possibility of rotor stall is increased at high density
altitudes; therefore, avoid flight at high density altitudes.
(3) Use maximum ``power-on'' RPM at all times during powered
flight.
(4) Avoid sideslip during flight. Maintain in-trim flight at all
times.
(5) Avoid large, rapid forward cyclic inputs in forward flight,
and abrupt control inputs in turbulence.
Emergency Procedures Section
(1) RIGHT ROLL IN LOW ``G'' CONDITION
Gradually apply aft cyclic to restore positive ``G'' forces and
main rotor thrust. Do not apply lateral cyclic until positive ``G''
forces have been established.
(2) UNCOMMANDED PITCH, ROLL, OR YAW RESULTING FROM FLIGHT IN
TURBULENCE.
Gradually apply controls to maintain rotor RPM, positive ``G''
forces, and to eliminate sideslip. Minimize cyclic control inputs in
turbulence; do not over control.
(3) INADVERTENT ENCOUNTER WITH MODERATE, SEVERE, OR EXTREME
TURBULENCE.
If the area of turbulence is isolated, depart the area;
otherwise, land the helicopter as soon as practical.
(b) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used when approved by the Manager, Rotorcraft Standards Staff, FAA,
Rotorcraft Directorate. Operators shall submit their requests
through an FAA Principal Operations Inspector, who may concur or
comment and then send it to the Manager, Rotorcraft Standards Staff.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Rotorcraft Standards Staff.
(c) Special flight permits, pursuant to sections 21.197 and
21.199 of the Federal Aviation Regulations (14 CFR 21.197 and
21.199), will not be issued.
(d) This amendment becomes effective on March 17, 1995.
Issued in Fort Worth, Texas, on February 23, 1995.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 95-5096 Filed 3-1-95; 8:45 am]
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