# NTSB ERA11LA507: Mitsubishi MU-2B-25, N344KL, Atlanta, GA, September 28, 2011

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: September 28, 2011, 17:15 local (21:15 UTC)
- Place: Atlanta, GA
- Coordinates: 33.013889, -84.61222 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.0139&lon=-84.6122&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Defining event: [Landing: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report October 9, 2012
- Report: Approved by Office Director
- NTSB office: Eastern Region Aviation
- Parties: FAA Atlanta FSDO
- NTSB case key (mKey): 81926
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA11LA507
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81926/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81926
- Page: https://openairdocs.org/ntsb/ERA11LA507

## Probable cause

The improper installation of the nose landing gear strut and subsequent collapse of the nose landing gear during landing.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Maintenance personnel; cases with it: [Mitsubishi MU-2B-25, 1 case](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=5780409), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md)
- [Landing gear system: nose/tail gear strut/axle](https://openairdocs.org/ntsb-findings/01023222): Aircraft › Aircraft systems · Inadequate inspection; cases with it: [Mitsubishi MU-2B-25, 1 case](https://openairdocs.org/ntsb-findings/01023222/cases.md?model=5780409), [All aircraft, 36 cases](https://openairdocs.org/ntsb-findings/01023222/cases.md)
- [Design: design of document/info](https://openairdocs.org/ntsb-findings/04011020): Organizational issues › Development · Manufacturer; cases with it: [Mitsubishi MU-2B-25, 1 case](https://openairdocs.org/ntsb-findings/04011020/cases.md?model=5780409), [All aircraft, 11 cases](https://openairdocs.org/ntsb-findings/04011020/cases.md)
- [Landing gear system: nose/tail landing gear](https://openairdocs.org/ntsb-findings/01023220): Aircraft › Aircraft systems · Incorrect service/maintenance (probable cause); cases with it: [Mitsubishi MU-2B-25, 1 case](https://openairdocs.org/ntsb-findings/01023220/cases.md?model=5780409), [All aircraft, 185 cases](https://openairdocs.org/ntsb-findings/01023220/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: [Mitsubishi MU-2B-25, 1 case](https://openairdocs.org/ntsb-events/040/sequence.md?model=5780409), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md)
- [Landing: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Mitsubishi MU-2B-25, 1 case](https://openairdocs.org/ntsb-events/330/sequence.md?model=5780409), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md)
- [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [Mitsubishi MU-2B-25, 1 case](https://openairdocs.org/ntsb-events/094/sequence.md?model=5780409), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md)

## Analysis

The pilot stated that after landing, the nose landing gear collapsed. Examination of the airplane nose strut down-lock installation revealed that the strut on the right side of the nose landing gear trunnion was installed incorrectly; the strut installed on the right was a left-sided strut. Incorrect installation of the strut could result in the bearing pulling loose from the pin on the right side of the trunnion, which could allow the nose landing gear to collapse. A review of maintenance records revealed recent maintenance activity on the nose gear involving the strut. The design of the strut is common for the left and right. Both struts have the same base part number, and a distinguishing numerical suffix is added for left side and right side strut determination. If correctly installed, the numbers should be oriented facing outboard. The original MU-2 Maintenance Manual did not address the installation or correct orientation of the strut. The manufacturer issued MU-2 Service Bulletin (SB) No. 200B, dated June 24, 1994, to address the orientation and adjustment. Service Bulletin 200B states on page 8 of 10 that the “Part Number may be visible in this (the) area from the out board sides (Inked P/N may be faded out).”

## Factual narrative

On September 28, 2011, at 1715 eastern daylight time, a Mitsubishi MU-2B-25, N344KL, registered to Laurel Mountain Aviation LLC, experienced a nose landing gear collapse during landing roll out at Cobb County Airport-McCollum Field (RYY), Atlanta, Georgia. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed. The corporate flight was operated under the provisions of 14 Code of Federal Regulations Part 91. The airplane received structural damage to the airplane nose and structure aft of the primary bulkhead. The certificate airline transport rated pilot and two passengers reported no injuries. The flight originated from Huntsville International Airport-Carl T. Jones Field (HSV), Huntsville, Alabama, at 1541 central daylight time. The pilot stated that after departing HSV, he climbed to his cruise altitude of 11,000 feet mean sea level. Upon arrival in the vicinity of RYY, he was cleared for a visual approach to runway 27. He entered a right closed traffic pattern and completed all required checklist items. The airplane touched down on the runway and the nose landing gear collapsed. The airplane came to rest upright on the runway. Examination of the airplane nose strut down lock installation revealed the strut, part number (PN) 010A-39117-11, that was installed on the right side of the nose landing gear trunnion, was installed incorrectly. The bearing "stake marks" should have been on the outboard side of the 010A-39117 strut. Incorrect installation of the strut could result in the bearing pulling loose from the pin on the right side of the trunnion. A review of maintenance records revealed recent maintenance activity on the nose gear involving the strut. The design of the strut is typical for the left and right. Both struts have the base PN 010A-39117, permanently marked by cast numbers on the outboard side of the strut. According to the manufacturer, the part should display the PN 010A- 39117-12 for the right and -11 for the left. The manufacturer issued MU-2 Service Bulletin (SB) No. 200B, dated June 24, 1994, to address the orientation and adjustment. The MU-2 Maintenance Manual did not address the installation or correct orientation of the strut. Service Bulletin 200B states on page 8 of 10 that the “Part Number may be visible in this (the) area from the out board sides (Inked P/N may be faded out)”. The accident strut only exhibited the base number. The left strut was installed in accordance with the SB. The last annual and 200-hour inspection was conducted on July 11, 2011, 10 hours before the accident. The airplane was flown to a repair station for additional maintenance prior to the accident. The airplane had a previous nose landing gear failure and had been repaired by the pilot's mechanic. A mechanic at the repair station looked at the nose landing gear down lock and observed it only had a 2 millimeter clearance. The mechanic called the pilot and informed him the airplane did not have enoughdown lock engagement. The pilot informed the mechanic to fix the problem. The mechanic installed a short block PN 010A-39108-125 to get the proper engagement as outlined in the maintenance manual. A review of the logbooks revealed no determination could be made as to who had previously worked on the drag strut.

## Aircraft

- Registration: [N344KL](https://openairdocs.org/deregistered/N344KL-2012-06-15), registration cancelled 2012-06-15, S/N 257, built 1973 (OpenAirDocs)
- Reported make and model: MITSUBISHI MU-2B-25
- Registry model: [Mitsubishi MU-2B-25](https://openairdocs.org/model/mitsubishi-mu-2b-25) (registry code 5780409) (OpenAirDocs)
- Registry engine: [AiResearch TPE331-5&6SER](https://openairdocs.org/engine/airesearch-tpe331-5-6ser) (registry code 01515, turbo-prop) (OpenAirDocs)
- Category: Airplane
- Serial number: 257
- Airframe hours: 6196
- Engines: Honeywell TPR331-6-251M 715 horsepower turbo prop; Honeywell TPE331-6-251M 715 horsepower turbo prop
- Damage: Substantial damage
- Flight: Executive/Corporate, Part 91
- Operator: Laurel Mountain Aviation LLC
- Registered owner: Laurel Mountain Aviation LLC
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, June 27, 2011, 10 hours before
- Departed: HSV, Hunstville, AL
- Destination: RYY, Atlanta, GA
- Flight plan: IFR
- Airport: RYY, Cobb County Airport  Mc Collum, runway 27, 6,311 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 37; injuries: none; flight instructor, airline transport, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review May 2, 2011; seat: left; flight hours: 11,100 total, 1,500 in this make and model, 10,800 as pilot in command, 40 in the last 90 days, 20 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 66 °F, dew point 61 °F
- Altimeter: 29.90 inHg
- Observed at: RYY

## 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 20110928022269A](https://openairdocs.org/incident/20110928022269A), Sep 28, 2011: Mitsubishi MU-2B-25, Kennesaw, GA, Substantial damage. On September 28, 2011 aircraft N344KL sustained damage while landing at cobb county- Mccollum Field due to the collapse of the nose gear. This office was…

## Docket (19 files)

The files NTSB released with the investigation on July 30, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81926. 16.5 MB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 345 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354884&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF
- Statement Noblin (item 2, .PDF, 16 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40355125&FileExtension=.PDF&FileName=Statement%20Noblin-Master.PDF
- FAA Inspector Statement (item 3, .PDF, 69 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40355489&FileExtension=.PDF&FileName=FAA%20Inspector%20Statement-Redacted.PDF
- \Follow Up FAA Inspector Statement (item 4, .PDF, 46 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356267&FileExtension=.PDF&FileName=%5CFollow%20Up%20FAA%20Inspector%20Statement-Redacted.PDF
- Extract Logbooks (item 5, .PDF, 194 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354885&FileExtension=.PDF&FileName=Extract%20Logbooks-Redacted.PDF
- Diagram Drag Barce Strut Installation (item 6, .PDF, 21 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40355735&FileExtension=.PDF&FileName=Diagram%20Drag%20Barce%20Strut%20Installation-Master.PDF
- MU-2 Maintenance Manual Requirement (item 7, .PDF, 147 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354886&FileExtension=.PDF&FileName=MU-2%20Maintenance%20Manual%20Requirement-Master.PDF
- MU 2 Maintenance Manual Rigging (item 8, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354887&FileExtension=.PDF&FileName=MU%202%20Maintenance%20Manual%20Rigging-Master.PDF
- MU 2 Service News (item 9, .PDF, 749 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354888&FileExtension=.PDF&FileName=MU%202%20Service%20News-Master.PDF
- Service Bulletin June 24, 1994 (item 10, .PDF, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40355126&FileExtension=.PDF&FileName=Service%20Bulletin%20June%2024,%201994-Master.PDF
- Service Bulletin July 13 1981 (item 11, .PDF, 5.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40355137&FileExtension=.PDF&FileName=Service%20Bulletin%20July%2013%201981-Master.PDF
- Photo 1 View of right hand forward strut downlock mechanism. Photo FAA (item 12, .PDF, 517 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354889&FileExtension=.PDF&FileName=Photo%201%20View%20of%20right%20hand%20forward%20strut%20downlock%20mechanism.%20Photo%20FAA-Master.PDF
- Photo 2 View of nose wheel up lock switch. Photo FAA (item 13, .PDF, 821 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354890&FileExtension=.PDF&FileName=Photo%202%20View%20of%20nose%20wheel%20up%20lock%20switch.%20Photo%20FAA-Master.PDF
- Photo 3 View looking through failed casting to the left hand side. Photo FAA (item 14, .PDF, 428 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354891&FileExtension=.PDF&FileName=Photo%203%20View%20looking%20through%20failed%20casting%20to%20the%20left%20hand%20side.%20Photo%20FAA-Master.PDF
- Photo 4 View looking rearward at forward right hand strut. Photo FAA (item 15, .PDF, 926 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354892&FileExtension=.PDF&FileName=Photo%204%20View%20looking%20rearward%20at%20forward%20right%20hand%20strut.%20Photo%20FAA-Master.PDF
- Photo 5 View looking at left hand side forward strut. Photo FAA (item 16, .PDF, 776 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354893&FileExtension=.PDF&FileName=Photo%205%20View%20looking%20at%20left%20hand%20side%20forward%20strut.%20Photo%20FAA-Master.PDF
- Photo 6 Front view of airplane on the runway. Photo FAA (item 17, .PDF, 921 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40355164&FileExtension=.PDF&FileName=Photo%206%20Front%20view%20of%20airplane%20on%20the%20runway.%20Photo%20FAA-Master.PDF
- Photo 7 Right side view of airplane. Photo FAA (item 18, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40355165&FileExtension=.PDF&FileName=Photo%207%20Right%20side%20view%20of%20airplane.%20Photo%20FAA-Master.PDF
- Photo 8 Left side view of airplane. Photo FAA (item 19, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40355167&FileExtension=.PDF&FileName=Photo%208%20Left%20side%20view%20of%20airplane.%20Photo%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.

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