Safety Recommendation A-16-053
Details
Synopsis: These recommendations are intended to prevent the incorrect installation of the reversing lever (beta arm) and related components in PT6A engines, which can cause the propeller to transition uncommanded to feather in flight. They are derived from investigations of accidents in which the beta arm or related components were found incorrectly positioned. As a result of these investigations, the NTSB is issuing one safety recommendation each to the FAA and Pratt & Whitney Canada. During the NTSB’s on-scene wreckage examination of a Beech 1900C airplane that collided with terrain following a loss of thrust in the left engine (a Pratt & Whitney Canada PT6A-65B) shortly after takeoff from Miami Executive Airport, Miami, Florida, the left engine's propeller beta arm was found incorrectly positioned over its guide pin rather than under it. (Figure 1 shows exemplar engines with correctly and incorrectly positioned beta arms.) If the beta arm is not secure under the guide pin, the unsecured linkage could release oil pressure in the beta valve and cause uncommanded travel of the propeller to the feather position. Although metallurgical analysis during the NTSB’s investigation determined that the incorrect beta arm position was a result of impact or postaccident forces and therefore not causal to the accident, the incorrect position of the component was identified as a finding in the investigation.
Recommendation: TO THE FEDERAL AVIATION ADMINISTRATION: Issue a special airworthiness information bulletin that directs maintenance personnel, during routine scheduled inspections of and after propeller installation on Pratt & Whitney model PT6A engines, to visually verify that the propeller reversing lever (beta arm) and guide pin are correctly installed and, if necessary, to fix any improper installations.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Alternate Action
Mode: Aviation
Location: Miami, FL, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: ERA15FA129
Accident Reports:
Report #: ASR-16-07
Accident Date: 2/11/2015
Issue Date: 12/8/2016
Date Closed: 1/25/2021
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Alternate Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 1/25/2021
Response: We note that, on February 27, 2020, you published Safety Alert for Operators (SAFO), “Pratt & Whitney Canada Model PT6A Engines,” which recommends that, during routine scheduled inspections of these engines before and after propeller installation, maintenance personnel and facilities visually verify that the propeller-reversing lever, or beta arm, and guide pin are correctly installed and, if necessary, fix any improper installations. We believe the SAFO guidance is responsive to this recommendation and, because this is a maintenance issue and not related to certification, we continue to believe that your decision to publish a SAFO is an acceptable alternative to the SAIB that we recommended. Accordingly, Safety Recommendation A-16-53 is classified CLOSED--ACCEPTABLE ALTERNATE ACTION.

From: FAA
To: NTSB
Date: 9/4/2020
Response: -From Steve Dickson, Administrator: The Federal Aviation Administration (FAA) published Safety Alert for Operators (SAFO) 20002, Pratt & Whitney Canada Model PT6A Engines, on February 27, 2020. This SAFO alerts operators, owners, and maintenance providers of aircraft with PT6A engines (specifically the Pratt & Whitney Canada model) of a safety issue regarding the incorrect installation of reversing levers (beta arms) and guide pin. Depending on airplane make and model, warnings about this issue in aircraft maintenance manuals vary, ranging from a general warning about the hazards of a misadjusted beta valve assembly, to no warning at all. In March 2016, Pratt & Whitney Canada issued Service Letter PT6A-239R1, Reversing lever guide pin bracket assembly, to alert operators about the hazards of incorrectly installing the propeller beta arm. Pratt & Whitney Canada also revised the PT6A engine maintenance and overhaul manuals, and a future plan is to redesign the guide pin. Maintenance personnel and facilities should visually verify that the propeller reversing lever (beta arm), and guide pin are properly installed on all Pratt & Whitney Canada model PT6A engines during routine scheduled inspections both before and after propeller installation. If improper installations are found, they should be fixed by certificated and qualified technicians. These visual inspections should not only detect errors, but also heighten awareness in the maintenance community about the importance of proper installation of the reversing levers (beta arm) and guide pin. I believe the FAA has effectively addressed Safety Recommendation A-16-53 and consider our actions complete.

From: NTSB
To: FAA
Date: 8/7/2018
Response: We previously told you that a safety alert for operators (SAFO) would be an acceptable alternate solution to satisfy this recommendation, as this is a maintenance issue and not related to certification. We note that, due to other safety priorities and organizational changes, your work on the SAFO has been delayed until later this year. In the meantime, Safety Recommendation A-16-53 remains classified OPEN--ACCEPTABLE ALTERNATE RESPONSE.

From: FAA
To: NTSB
Date: 5/30/2018
Response: -From Daniel K. Elwell, Acting Administrator: The Federal Aviation Administration’s (FAA) Aircraft Maintenance Division continues to work on the publication of a Safety Alert for Operators (SAFO). However. due to other safety priorities and changes within our organization, the estimated completion date is September 30. 2018. We will forward the SAFO to the Board once it is published. I will keep the Board informed of the FAA ·s progress on this recommendation and provide an update by January 2019.

From: NTSB
To: FAA
Date: 5/4/2017
Response: During our December 16, 2016, meeting regarding the issue with the propeller-reversing lever (beta arm) and guide pin, you indicated that, because this is a maintenance issue and not related to certification, a safety alert for operators (SAFO) would be more appropriate than an SAIB. We agreed that a SAFO would be an acceptable alternate solution, and we look forward to reviewing the SAFO once it has been published. In the meantime, Safety Recommendation A 16-53 is classified OPEN--ACCEPTABLE ALTERNATE RESPONSE.

From: FAA
To: NTSB
Date: 2/13/2017
Response: -From Michael P. Huerta, Administrator: On December 16, 2016, the Board and the Federal Aviation Administration (FAA) discussed the propeller reversing lever (beta arm) and guide pin issue. It was agreed that issuing a Safety Alert for Operators (SAFO) as an alternative would better address this issue. We expect to complete this SAFO before the end of2017. We will forward the SAFO to the Board once it is published. I will keep the Board informed of the FAA's progress on this safety recommendation and provide an update before the end of 2017.

From: NTSB
To: FAA
Date: 12/8/2016
Response: On December 5, 2016, we adopted our report about preventing the incorrect installation of the reversing lever (beta arm) in Pratt & Whitney Canada PT6A engines.1 Additional information about the investigative background and analysis that led to the resulting recommendations may be found in the safety recommendation report, which can be accessed at our Aviation Information Resources webpage under NTSB report number ASR-16-007. As a result of this investigation, we issued one new recommendation to Pratt & Whitney Canada and the following new recommendation to the Federal Aviation Administration.