Discussion
On September 10, 1998, the FAA issued priority letter AD 98-19-15, which applies to Fairchild SA226 and SA227 airplanes that are equipped with Barber-Colman pitch trim actuators, P/N 27-19008-001 or P/N 27-19008-002. That AD resulted from reports of two incidents of abrupt movement of the horizontal stabilizer to or near the full airplane nose-up position. These two incidents involved mechanical failure of these Barber-Colman pitch trim actuators. In the latest incident, the airplane experienced an upset that resulted in a 42-degree nose-up pitch with the airspeed decreasing to 79 knots indicated airspeed (IAS). The other incident was very similar to the one described above.
AD 98-19-15 requires incorporating the following information into the applicable AFM:
"Limit the maximum indicated airspeed to maneuvering airspeed (Va) as shown in the appropriate airplane flight manual (AFM)."
and
The minimum crew required is two pilots."The speed restriction is intended to assure that the airplane is at a manageable speed while the pilots tend to the control forces that would be present during a pitch up condition, and successfully operate and land the airplane.
The two-pilot requirement is based on the comments received from those that were involved in the investigation/analysis of the two incidents. Both incidents were with two pilots in the airplane, and the comments indicated that the forces involved required two pilots. When the actuator fails in the full leading edge down position and the actuator fails to retrim, the column forces exceed the temporary force limits for one pilot. One pilot may not be able to sustain the forces required to continue safe flight and landing. In addition, having two pilots has proven beneficial in other cases of aircraft that have sustained control system malfunctions resulting in high control forces and/or limited control power. Two pilots also gives one a chance to tuneradios, read the navigation equipment, and communicate with air traffic control, as needed.
Operators of SA226 and SA227 series airplanes, except for the commuter category Models SA227-CC and SA227-DC airplanes, may avoid the restrictions of this AD by installing an airworthy Simmonds-Precision actuator, P/N DL5040M5 or P/N DL5040M6, in place of the affected Barber-Colman actuator. The Simmonds-Precision actuators are not approved for the Models SA227-CC and SA227-DC airplanes.
In addition, this AD does not affect AD 97-23-01, Amendment 39-10188 (62 FR 5922, November 3, 1997). AD 97-23-01 still applies to all SA226 and SA227 series airplanes equipped with either Barber-Colman or Simmonds-Precision pitch trim actuators, and requires the following:
- Repetitively measuring the freeplay of the pitch trim actuator and repetitively inspecting the actuator for rod slippage or ratcheting;
- Immediately replacing any actuator if certain freeplay limitations are exceeded or rod slippage or ratcheting is evident; and,
- Eventually replacing the Simmonds-Precision actuators regardless of the inspection results.
Relevant Service Information
Fairchild has issued the following service letters that specify limiting the maximum indicated airspeed to maneuvering airspeed (Va) as shown in the appropriate airplane flight manual (AFM), operating the aircraft with two pilots, and other operating instructions, to lessen the severity of airplane pitch up in case of failure of the subject actuators:
Service Letter 226-SL-017, FAA Approved: August 26, 1998; Revised: September 2, 1998.
Service Letter 227-SL-033, FAA Approved: August 26, 1998; Revised: September 2, 1998.
Service Letter CC7-SL-023, FAA Approved: August 26, 1998; Revised: September 2, 1998.
The FAA's Determination and Explanation of the AD
Since an unsafe condition was identified that is likely to exist or develop in other Fairchild Aircraft SA226 and SA227 series airplanesof the same type design airplanes that are equipped with Barber-Colman pitch trim actuators, part number (P/N) 27-19008-001 or P/N 27-19008-002, the FAA:
- Determined that immediate AD action should be taken to lessen the severity of airplane pitch up caused by mechanical failure of the pitch trim actuator, which could result in a pitch upset and structural failure of the airplane; and
- Issued AD 98-19-15 as a priority letter on September 10, 1998.
Because of the seriousness of the issue and in order to assure the continued airworthiness of the SA226 and SA227 series airplanes, the FAA determined that the speed restriction and minimum pilot requirement are necessary while a mechanical fix is being researched and developed for the affected Barber-Colman pitch trim tab actuators.
At the present time, there is a design alternative to the Barber-Colman pitch trim actuators for the affected airplanes, except for the Models SA227-CC and SA227-DC airplanes. This alternative isthe Simmonds-Precision pitch trim actuator, P/N DL5040M5 or P/N DL5040M6. The goal is to find, approve, and eventually require a mechanical fix for all of the SA226 and SA227 series airplanes equipped with Barber-Colman pitch trim actuators, instead of imposing the speed restriction and minimum pilot requirement.
Determination of the Effective Date of the AD
Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on September 10, 1998, to all known U.S. operators of Fairchild SA226 and SA227 series airplanes that are equipped with Barber-Colman pitch trim actuators, P/N 27-19008-001 or P/N 27-19008-002. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) tomake it effective as to all persons.
Comments Invited
Although this action is in the form of a final rule that involves requirements affecting immediate flight safety and, thus, was not preceded by notice and opportunity to 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 above. 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 ofthe 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. 98-CE-84-AD." The postcard will be date stamped and returned to the commenter.
Regulatory Impact
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 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. 106(g), 40113, 44701.
39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: