Boeing 737-3B7 incident near Charlotte (Clt), North Carolina, July 15, 2009
On July 15, 2009 at about 1:30 pm local time, a Boeing 737-3B7, registered N506AU, suffered minor damage in an incident during prior to flight near Charlotte (Clt), North Carolina (Douglas International airport). It was flown under scheduled airline rules (Part 121). No one was hurt.
The NTSB's probable cause their words, unchanged
The failure of the left hand main landing gear was caused by heat induced cracks resulting from abusive grinding/polishing of the chrome plate that was applied during the last overhaul.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 15, 2009 · about 1:30 pm local time
- Place
- Charlotte (Clt), North Carolina · Douglas International · map
- Type
- Incident
- Injuries
- No one was hurt.
- Weather
- not recorded
- Aircraft
- Boeing 737-3B7 · all 737-3B7s on the register
- Registration
- N506AU · no longer on the register · serial 23381
- Damage
- Minor damage
- Flight
- Flight · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
On July 15th, 2009, US Airways reported that the Left Hand (LH) Main Landing Gear (MLG) from the incident airplane was found to have a hydraulic fluid leak through a pin hole on the forward side of the outer cylinder. The leaking gear was sent to AAR Landing Gear Services (LGS) where ultrasonic inspection found crack indications approximately 31 inches from the open end of the outer cylinder. The main landing gear was disassembled and subsequent magnetic particle inspection found a long, sharp indication through the chrome plating in the working inner diameter (ID) section of the outer cylinder. The subject outer cylinder was sent to Boeing Material and Process Technology in Seattle Washington for fracture analysis. It was reported that the subject outer cylinder had been through three overhauls, the first two being performed by US Airways. It was further reported that during the first two overhauls, US Airways did not perform any rework on the working ID of the cylinder. AAR performed the last overhaul and it was reported that at that time, corrosion was found and removed from the working ID section of the cylinder in accordance with the component maintenance manual (CMM). The oversized ID surface was then chrome plated and ground to the design diameter. AAR overhauled the LH MLG in December 2008, and it was installed in the incident airplane in April 2009. The subject gear accumulated a total cycles of 40,639 (379 since last overhaul) and a total hours of 59,837 (606 since last overhaul). A crack measuring 1.95” was present on the working ID on the forward side of the outer cylinder. Several microcracks of varying lengths were also found present on this region. The primary crack was made up of three cracks that had linked together. The cracks originated from heat induced cracks that were present on the ID surface and propagated primarily by fatigue towards the outer diameter (OD) surface of the cylinder. The microcracks that were present on the region originated and propagated in a similar manner. The heat induced cracks were the result of abusive grinding/polishing of the chrome plate that was applied during the last overhaul.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Aircraft maintenance event during prior to flight
- Aircraft maintenance event during standing (engine(s) not oper)
- Aircraft structural failure defining event
The NTSB's findings
- Aircraft › Aircraft systems › Landing gear system › Main landing gear › Damaged/degraded
- Aircraft › Aircraft systems › Landing gear system › Main landing gear › Fatigue/wear/corrosion
- cause Aircraft › Aircraft systems › Landing gear system › Main landing gear › Incorrect service/maintenance
Crew member
No details recorded.
The aircraft
- Last inspection: inspection type not recorded
- Maximum gross weight: 135,000 lb
- Landing gear: retractable
- Engine 1: Cfm Intl. CFM56 SERIES (turbofan); 0 hours total
- Engine 2: Cfm Intl. CFM56 SERIES (turbofan); 0 hours total
- Operator: US Airways INC
The flight
- Flight plan: not recorded
- A second pilot was aboard
Weather at the time
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.