You may be trying to access this site from a secured browser on the server. Please enable scripts and reload this page.
Turn on more accessible mode
Turn off more accessible mode
Skip Ribbon Commands
Skip to main content
Top Link Bar
NEWS & EVENTS
Speeches & Testimony
Most Wanted List
The Investigative Process
Data & Stats
General Aviation Safety
Assistance to Families & Victims
Operations & Policy
Administrative Law Judges
Strategic Plans & Reports
Safety Recommendation Details
The Investigative Process
Data & Stats
General Aviation Safety
On June 7, 2013, about 0925 coordinated universal time, an EMB-145LR, registration B-3052, operating as China Eastern Airlines flight MU2947, departed the left side of runway 18L onto taxiway A2 while landing at Hongqiao International Airport, Shanghai, China, in moderate rain. The flight originated from Huai’an Lianshui Airport, Jiangsu, China. The 25 crewmembers and 44 passengers were uninjured, and the nose landing gear sustained minor damage.2 After this incident, the nosewheel steering manifold assembly and electrohydraulic servo valve (EHSV) were tested by the components’ manufacturers (Parker Aerospace and Woodward HRT, respectively) according to their returned component acceptance test protocols, which are the same tests that newly manufactured components would undergo before delivery.
TO THE FEDERAL AVIATION ADMINISTRATION: (1) Review Woodward HRT’s manufacturing process and quality control program for the electrohydraulic servo valve and require improvements to eliminate manufacturing or assembly errors and nonconformances that could cause uncommanded nosewheel steering anomalies in Embraer EMB-135, EMB-140, and EMB-145 aircraft; and (2) monitor and verify the effectiveness of any improvements.
Original recommendation transmittal letter:
Open - Acceptable Response
Addressee(s) and Addressee Status:
FAA (Open - Acceptable Response)
Safety Recommendation History
On April 13, 2017, you wrote that Woodward HRT investigated its manufacturing process and quality control program for the EHSV and made improvements based on its findings. You also discussed that you had done the following: • Inspected Woodward HRT’s manufacturing process, assembly process, and quality control program for the EHSV. • Verified the effectiveness of Woodward HRT’s improvements. • Implemented a new risk assessment for Woodward HRT. • Increased certificate management oversight. When we replied on September 21, 2017, we asked several questions to help us determine if these actions fully satisfied the recommendation, which you answered in your most recent letter. However, we note that our report issuing this recommendation described a condition in which a dimension critical to preventing O-ring deterioration—which was required to be inspected as part of a service bulletin—was outside of tolerance limits. When we asked if you had witnessed and audited the processes related to the dimensional noncompliance and, if so, what your findings were, you replied that, on February 7, 2017, you observed EHSV assembly and inspection at Woodward HRT and did not identify any nonconforming conditions. You asked that we clarify which critical dimension was found to be out of tolerance and where it was observed in the build process. Embraer issued Service Bulletin (SB) 145-32-0099 (current revision 03, dated April 8, 2005) to address premature deterioration of O-ring seals within the EHSV. The SB requires that the manifold assembly be fitted with an EHSV that has been screened and meets the requirements of HR Textron document DV1719. During our investigation of the August 29, 2011, incident when an EMB-145XR, operated by ExpressJet Airlines as United Express flight 5821, departed the left side of runway 10 during landing at Quad City International Airport in Moline, Illinois, we found that the C1 filter plug outer diameter was measured at 0.2077 inch, and the C2 filter plug outer diameter was measured at 0.2075 inch. These dimensions did not meet the requirements of HR Textron document DV1719, which requires the filter plugs’ outer diameters to be 0.2088–0.2093 inch. As the outer diameter of the filter plug decreases, the gap between the filter plug and the filter bore increases. The orifice filter seal seats against this gap. Per the manufacturer, as this gap increases, so does the tendency of the corresponding orifice filter seal to extrude. Our investigation found that the nosewheel steering manifold assembly had been upgraded per SB 145 32 0099, but the EHSV contained degraded O-rings. Postincident examination of the EHSV revealed that this dimension that is critical to preventing deterioration of the damaged O ring—and which was required to be inspected as part of the upgrade recommended in the SB—was outside of tolerance limits. Based on the information provided, you have largely satisfied this recommendation. The only remaining action is for you to act on the information we have provided in this letter related to the dimension critical to preventing O-ring deterioration. Pending that action, Safety Recommendation A-17-4 remains classified OPEN--ACCEPTABLE RESPONSE.
-From Daniel K. Elwell, Acting Administrator: In our initial letter to the Board, dated April 13, 2017, the Federal Aviation Administration (FAA) summarized the Woodward Hydraulic Research Textron (HRT) investigation into its manufacturing process and quality control program for the electrohydraulic servo valve (EHSV): improvements made by Woodward HRT; and the FAA 's investigation and verification activities. In response. the Board’s September 21, 2017. letter asked follow-up questions to determine if the FAA's actions were responsive to the recommendation. The FAA provides its response to these questions below. • .. Which FAA office performed the February 7, 2017, inspection at Woodward HRT in Valencia, California?'" An Aviation Safety Inspector (ASI) from the Van Nuys. California, Manufacturing Inspection District Office (now known as the Los Angeles/Van Nuys MIDO) conducted the inspection at Woodward HRT. • ··when did Woodward HRT investigate each manufacturing and inspection operation for the EHSV?'" Woodward HRT conducted a review of the complete build process of the EHSV with their customer, Parker Hannifin Corporation, on May 6-9, 2014. • "Did you or Woodward HRT use the 5S technique?" Woodward HRT conducted a review of the complete build process using the Kaizen 5S technique. which determined the flow grind process was the source of the foreign object debris (FOO) found in the EI ISV. • ··Did you witness and audit the processes related to these additional types of FOD [segments of 0 -ring left in the hydraulic chamber during manufacture, and assembly nu id on the armature] and to the dimensional noncompliance? If so, what findings were identified?" Segments of 0-Ring left in Hydraulic Chamber: Woodward HRT inspected the EHSV assembly process and discovered a nozzle plug tool's dimensional interference with the EHSV housing. This cut the 0-ring during the assembly process. which introduced debris inside the hydraulic chamber. Woodward I IRT redesigned the nozzle plug tool to reduce the dimensional interference. The FAA ASI audited Woodward I IRT's corrective actions addressing the deficiencies found during their review. Our audit included review of the revised procedures and work instructions, personnel training, use of technical data, redesigned tooling, handling and storage of workstation materials, and housekeeping practices. The FAA observed the operator’s assembly techniques and awareness of FOO cause/prevention. The r AA determined that Woodward HRT implemented effective corrective actions. Assembly Fluid on the Armature: The cut 0 -ring caused fluid to make its way to the armature. As part of the revised assembly processes and work instructions. Woodward HRT cleans and inspects the EHSY to eliminate FOD prior to installing the housing cover. This inspection includes ensuring fluid is not on the armature. The FAA observed operator assembly techniques and their awareness of FOD cause/prevention. The FAA determined that Woodward HRT implemented effective corrective actions. Inspection of Critical Dimension to Prevent 0-ring Deterioration: The Board’s safety recommendation report ASR-17-02, Uncommanded Nosewheel Steering Anomalies during Landing in Embraer EMB-145 Regional Jets. referenced an Embraer Service Bulletin (SB) that includes instructions to modify the nosewheel steering hydraulic manifold assembly with a new EHSV. The Board’s report described a condition in which a dimension critical to preventing 0-ring deterioration- of which an inspection was required as part of a recommended upgrade in SB 145-32-0099- was outside of tolerance limits. On February 7, 2017, the FAA observed the assembly and inspection of an EHSV at Woodward HRT and did not identify any nonconforming conditions. We request the Board clarify what critical dimension it found to be out of tolerance and where it was observed in the build process. • ··You told us that you witnessed the flow grind process and inspected the work areas and production valves; however, it is unclear if you audited the entire build process. Please clarify the specific processes that you witnessed on February 7, 2017." Woodward HRT conducted a review of the complete build process with their customer, Parker Hannifin Corporation, on May 6-9, 2014. In our February 7, 201 7, inspection at Woodward HRT, the FAA focused on major steps in the manufacturing and testing of the EHSV. This included FAA observation of the following operations: pressure check, flat lap. nozzle fit, flow grind, lap bench operation. EHSV housing assembly cleaning, and housing assembly inspection. The FAA placed special emphasis on observing the flow grind operation because this was where the source of FOO was generated. The FAA did not identify any anomalies during the observed operations. Following receipt of the Boards' clarification on the dimension critical to preventing 0 -ring deterioration discussed above. the FAA will detem1ine the need for further action and provide an updated response.
We note that Woodward HRT investigated its manufacturing process and quality control program for the EHSV and made improvements based on its findings. In addition, we note that you: • Inspected Woodward HRT’s manufacturing process, assembly process, and quality control program for the EHSV. • Verified the effectiveness of Woodward HRT’s improvements. • Implemented a new risk assessment for Woodward HRT. • Increased certificate management oversight. • Plan to monitor future incidents reported through the continued operational safety reporting process. However, to help us determine if these actions are responsive to this recommendation, please answer the following questions: • Which FAA office performed the February 7, 2017, inspection at Woodward HRT in Valencia, California? • When did Woodward HRT investigate each manufacturing and inspection operation for the EHSV? • Did you or Woodward HRT use the 5S technique? • You told us that Woodward HRT determined that it was foreign object debris (FOD) caused by the assembly tool (not manufacturing errors or nonconforming parts) that resulted in the uncommanded nosewheel steering anomalies of the Embraer EMB-135, EMB-140, and EMB-145 aircraft. Although you described one potential cause of FOD and what was done to remedy it, our safety recommendation report regarding this issue listed two other types of FOD: segments of O-ring left in the hydraulic chamber during manufacture, and assembly fluid on the armature. Our report also described a condition in which a dimension critical to preventing O-ring deterioration—which was required to be inspected as part of a safety bulletin—was outside of tolerance limits. Did you witness and audit the processes related to these additional types of FOD and to the dimensional noncompliance? If so, what findings were identified? • You told us that you witnessed the flow grind process and inspected the work areas and production valves; however, it is unclear if you audited the entire build process. Please clarify the specific processes that you witnessed on February 7, 2017. Pending our receipt and review of this information, Safety Recommendation A-17-4 is classified OPEN--ACCEPTABLE RESPONSE.
-From Michael P. Huerta, Administrator: On February 7, 2017, the Federal Aviation Administration (FAA) conducted.an inspection at Woodward HRT in Valencia, California, to review the manufacturing process, assembly process, and quality control program for the electrohydraulic servo valve (EHSV). The FAA's inspection revealed that Woodward HRT conducted an investigation of each manufacturing and inspection operation for the EHSV, utilizing the Kaizen SS technique (a lean manufacturing tool that evaluates and improves quality, productivity, safety, and workplace culture). The intent of using the Kaizen 5S technique was to identify issues and develop improvements to Woodward HRT's quality control program for the EHSV product line in response to this safety recommendation. As a result, Woodward HRT determined it was the presence of foreign object damage (FOO) caused by the assembly tool and not manufacturing errors or nonconforming parts that resulted in the uncommanded nosewheel steering anomalies of the Embraer EMB-135, EMB-140, and EMB-145 aircraft. Woodward HRT determined its manufacturing "Flow Grind Process" was the source of the FOD found in the EHSV housing during the Board's investigation. Woodward HRT evaluated the process and determined tooling, materials, and lack of work area cleanliness were potential FOO sources during EHSV assembly. Woodward HRT: • Inspected the EHSV assembly tool and discovered a nozzle plug tool had dimensional interference with the EHSV housing. This caused the 0-ring to be cut and introduced debris inside the housing during assembly. Woodward HRT redesigned the tool to reduce the dimensional interference. The 0-ring placement was also shifted to eliminate the possibility of 0-rings being cut during assembly; • Evaluated the materials used in the EHSV manufacturing equipment and determined the lapping machine and work bench covers were potential FOD sources. The lapping machine had worn felt disc pads which introduced loose fibers. Woodward HRT replaced all the covers with new "fiber-free" pads to eliminate the possibility of FOD from loose pad fibers; • Determined that assembly personnel were also using incorrect material to cover work benches and to clean EHSV parts during assembly. Accordingly, Woodward HRT replaced the material with fiber-free wipes to cover work benches and to clean parts to eliminate potential FOD sources in the EHSV manufacturing process; and • Inspected the EHSV manufacturing and assembly work areas and found numerous workstations with clutter and debris. The company developed and implemented a FOD control program to eliminate potential EHSV contamination. The FAA verified the implementation of the FOO control program and found it to be satisfactory. The FAA conducted an inspection of the EHSV work areas and EHSV s in production and determined: • Woodward HRT's manufacturing process, assembly process, and tooling and quality control program to be satisfactory; • The EHSVs inspected were found to be in conformance to the design requirements; and • The manufacturing and assembly improvements to eliminate potential FOD sources were effective. In summary, the FAA investigated and verified that corrective actions were effective relating to the safety concerns identified in Safety Recommendation A-17-04. Based on the information gathered during the investigation, the FAA completed a new risk assessment for Woodward HRT and increased certificate management oversight. The certificate management oversight will include product audits to confirm that articles manufactured by Woodward HRT (e.g. EHSV) conform to type design requirements and are in a condition for safe operation. Finally, the FAA will monitor any future incidents reported through the Continued Operational Safety reporting process. In consideration of the identified improvements to Woodward HR T's manufacturing process, quality control program, and .increased FAA oversight, the FAA recommends closure of Safety Recommendation A-17-04.
On January 26, 2017, the National Transportation Safety Board (NTSB) adopted our safety recommendation report concerning uncommanded nosewheel steering anomalies during landing in Embraer EMB-145 regional jets. Additional information may be found in the safety recommendation report, which can be accessed at our website (www.ntsb.gov) under report number ASR-17-02. As a result, we issued five new recommendations, including two to Embraer and the following three recommendations to the Federal Aviation Administration.
Strategic Plan, Performance & Accountability Reports & More
Directions to Conference Center
Web Policies & Notices
Annual Review of Aircraft