# NTSB ERA12LA117: Piper PA-44-180, N790GK, Lawrenceville, GA, December 19, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 19, 2011, 11:00 local (16:00 UTC) - Place: Lawrenceville, GA - Coordinates: 33.978054, -83.962219 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.9781&lon=-83.9622&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report January 31, 2013 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO, Piper Aircraft, Inc. - NTSB case key (mKey): 82551 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA12LA117 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/82551/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=82551 - Page: https://openairdocs.org/ntsb/ERA12LA117 ## Probable cause The mechanic's improper installation and lubrication of the bushing on the right main landing gear truss assembly, which resulted in the landing gear not locking in the down position. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Maintenance](https://openairdocs.org/ntsb-findings/02062000): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Piper PA-44-180, 2 cases](https://openairdocs.org/ntsb-findings/02062000/cases.md?model=7104402), [All aircraft, 143 cases](https://openairdocs.org/ntsb-findings/02062000/cases.md) - [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Piper PA-44-180, 1 case](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=7104402), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md) - [Landing gear system: main landing gear](https://openairdocs.org/ntsb-findings/01023210): Aircraft › Aircraft systems · Malfunction (probable cause); cases with it: [Piper PA-44-180, 3 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md?model=7104402), [All aircraft, 241 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft maintenance event](https://openairdocs.org/ntsb-events/040); cases with it: [Piper PA-44-180, 4 cases](https://openairdocs.org/ntsb-events/040/sequence.md?model=7104402), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Piper PA-44-180, 11 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=7104402), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis While configuring the airplane for a power-off stall, the pilots noted that there was an unsafe gear indication after selecting the landing gear to the down position. The flight instructor made several unsuccessful attempts to extend the landing gear using the emergency gear extension procedures, but the light did not illuminate. The pilot reported the condition to the air traffic controller, and he maneuvered the airplane for a low approach, and the controller advised the pilot that the gear appeared to be down. During the landing roll all three landing gears remained extended, but as the airplane slowed, the right main landing gear collapsed, and the airplane veered off the runway colliding with a runway light. A postaccident examination of the right main landing gear revealed that the truss assembly hook assembly did not travel over the truss pin. The landing gear was tested, and the right main landing gear did not lock on any attempt. In addition, the right main landing gear truss bracket and stud had excessive friction and prevented the side brace from fully rotating, subsequently preventing the truss hook from traveling over the lock pin. The right main landing gear truss bracket pin had little or no grease present; however, the left main landing gear truss bracket pin had grease indications around the pin and zerk fitting. A review of the airframe maintenance records indicated that about a month before the accident, the airplane had completed a 100-hour inspection and a side brace mount assembly was installed in the right main landing gear. The mechanic who performed the maintenance stated that he could not find any guidance in the maintenance manual on how to remove and install the new bushing; therefore, he replaced the bushing and verified that there was movement between the two parts, and then reinstalled the side brace assembly on the airplane. The mechanic did not follow the proper procedures as described in the manufacturer maintenance manual. The accident occurred about 38 hours after the 100-hour inspection. ## Factual narrative On December 19, 2011, at 1100, eastern standard time, a Piper PA-44-180, N790GK, registered to and operated by Airline Transport Professionals (ATP), incurred substantial damage when the right main gear collapsed during the landing roll at the Gwinnet County Airport (LZU), Lawrenceville, Georgia. The flight instructor and pilot rated student were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the 14 Code of Federal Regulations Part 91, instructional flight. The flight originated, earlier that day, from the DeKalb-Peachtree Airport (PDK), Atlanta, Georgia, about 1000. While configuring the airplane for a power off stall, the pilots noted an unsafe gear indication after selecting the landing gear down position. There were two green lights, but the right main landing gear indicator light was not on. The flight instructor recycled the landing gear, but right main landing gear indicator light did not illuminate. The flight instructor changed the landing gear indicator light bulbs in an unsuccessful attempt to get the right main landing gear indicator light to ignite. He recycled the landing gear five more times, but the light still did not illuminate. The flight instructor followed the emergency landing gear extension procedures in the pilot’s operating handbook (POH), but the right main landing gear indicator light would not illuminate. The pilots reported the condition to an air traffic controller and he maneuvered the airplane for a low approach and the controller advised them that the gear appeared down. The flight instructor then entered the traffic pattern and landed on runway 07. During the landing, all three main landing gear were extended, but as the airplane slowed, the right main landing gear collapsed, the airplane veered off the runway, and struck a runway light. The airplane incurred damage to the right engine’s propeller, right wing outboard leading edge, right flap, and the right aileron incurred structural damage. The airplane was manufactured in 1979 and was equipped with two Lycoming O-360 series, 180-horsepower engines. The airplane's most recent 100-hour inspection was completed on November 16, 2011. At the time of the inspection, the reported aircraft time was 9781.3 total hours and the recorded hobbs time was 7073.6 hours. The accident occurred about 38 hours after the most recent 100-hour inspection. A postaccident examination of the right main landing gear revealed that the truss assembly hook assembly did not travel over the truss pin. Federal Aviation Administration inspectors tested the landing gear and the right main landing gear did not lock on any attempt. In addition, the right main landing gear truss bracket and stud had excessive friction and prevented the side brace from fully rotating, subsequently preventing the truss hook from traveling over the lock pin. The right main landing gear truss bracket pin had little or no grease present; however, the left main landing geartruss bracket pin had grease indications around the pin and zerk fitting. A review of the airframe maintenance records indicated that a new bushing was installed in the right main landing gear side brace mount assembly on November 16, 2011. The mechanic who performed the maintenance stated that he could not find any guidance in the maintenance manual on how to remove and install the new bushing; therefore, he replaced the bushing and verified that there was movement between the two parts, and then reinstalled the side brace assembly on the airplane. In the same maintenance entry the mechanic noted that he greased the landing gear and performed a landing gear retraction, extension, and free-fall test without defects. The Piper Aircraft PA-44-180/180T Airplane Maintenance Manual, Page 32-15, Installation of the Main Landing Gear, indicated that the procedures for installing the gear side brace link assembly were: A. Position link support bracket with swivel stud installed at its attachment point on the web of the spar and secure with bolts and washers. B. Ascertain that the upper and lower links are assembled with downlock hook, retraction fitting, c.. attached, and through travel of the links and downlock hook clearance checked. C. Attach the upper link to the swivel stud of the support fitting and secure with bolt, bushing, washer, nut and cotter pin. D. The actuating cylinder rod end bearing and lower side brace link may be attached respectively to the retraction fitting and strut housing during the adjustment of the landing gear. In addition, the airplane maintenance manual stated "when assembling components of the landing gear, lubricate bearings, bushings, and friction surfaces with proper lubricant as described in Chapter 12." ## Aircraft - Registration: [N790GK](https://openairdocs.org/aircraft/N790GK), registered now, S/N 44-7995316, built 1979 (OpenAirDocs) - Reported make and model: PIPER PA-44-180 - Registry model: [Piper PA-44-180](https://openairdocs.org/model/piper-pa-44-180) (registry code 7104402) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 44-7995316 - Airframe hours: 9819 - Engines: LYCOMING O&VO-360 SER 180 horsepower reciprocating; LYCOMING O&VO-360 SER 180 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Airline Transport Professionals Corp Of USA - Registered owner: Airline Transport Professionals Corp Of USA - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, November 16, 2011, 38 hours before - Departed: PDK, Atlanta, GA - Destination: LZU, Lawrenceville, GA - Airport: LZU, Gwinnett County Airport, runway 07, 6,000 × 1,000 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 28; injuries: none; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review June 29, 2010; seat: right; flight hours: 1,212 total, 312 in this make and model, 123 in the last 90 days, 64 in the last 30 days, 3 in the last 24 hours - Student pilot; age 41; injuries: none; private; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review December 20, 2011; seat: left; flight hours: 360 total, 5 in this make and model, 260 as pilot in command, 5 in the last 90 days, 5 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 52 °F, dew point -8 °F - Altimeter: 30.35 inHg - Observed at: LZU ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20111219028589A](https://openairdocs.org/incident/20111219028589A), Dec 19, 2011: Piper PA-44-180, Lawenceville, GA, Minor damage. While performing manuevers, the pilots noticed a gear unsafe indication on the right main landing gear. The pilots checked the indicator lights, ran checklist,… ## Docket (11 files) The files NTSB released with the investigation on November 27, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=82551. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 953 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369155&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Reports from Federal Agencies: FAA Inspector's statement. (item 2, .PDF, 78 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40382386&FileExtension=.PDF&FileName=Reports%20from%20Federal%20Agencies%3A%20FAA%20Inspector%27s%20statement.-Master.PDF - FAA Statement (item 3, .PDF, 209 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369156&FileExtension=.PDF&FileName=FAA%20Statement-Redacted.PDF - Mechanic's Statement (item 4, .PDF, 74 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369158&FileExtension=.PDF&FileName=Mechanic%27s%20Statement-Redacted.PDF - Maintenance Logs (item 5, .PDF, 822 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369161&FileExtension=.PDF&FileName=Maintenance%20Logs-Redacted.PDF - Excerpt of Maintenance Maunal; Installation of Main Landing Gear (item 6, .PDF): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369163&FileExtension=.PDF&FileName=Excerpt%20of%20Maintenance%20Maunal;%20Installation%20of%20Main%20Landing%20Gear-Master.PDF - Safety Changes: Maintenance Procedural Changes (item 7, .PDF, 646 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369178&FileExtension=.PDF&FileName=Safety%20Changes%3A%20%20Maintenance%20Procedural%20Changes-Redacted.PDF - Weather Reports and Records (item 8, .PDF, 386 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369274&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 9, .PDF, 115 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40382384&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Photo 1; Overview of wreckage (courtesy of the FAA) (item 10, .PDF, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369131&FileExtension=.PDF&FileName=Photo%201;%20Overview%20of%20wreckage%20(courtesy%20of%20the%20FAA)-Master.PDF - Photo 2; Right Main Landing Gear Truss (courtesy of the FAA) (item 11, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369167&FileExtension=.PDF&FileName=Photo%202;%20Right%20Main%20Landing%20Gear%20Truss%20(courtesy%20of%20the%20FAA)-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.