Narrative:

I am submitting this report to report an unsafe working environment at the ZZZ maintenance hangar. The hangar floor; particularly under the heavy c-check area; is hollow and appears to be unstable. As I have learned since working here over the years; when this hangar was originally built in the 1940's the offices; bathrooms; hallways and such were all underground. This situation apparently worked fine for them; but they were building much smaller aircraft; in a factory setting. As of now; it appears that the basement has been backfilled and access to the basement obviously sealed off. In 2010; when a mechanic was using a floor jack to jack up an emb-170 left-hand (left/H) main landing gear (medium large transport); once the gear was lifted up the floor jack went right through the floor. I was present at that time and reached in the hole to get the jack that was lying on gravel about a foot underneath the floor. Inside the hole I could see a large open void which appeared to be a bathroom underneath the floor.management was informed of the incident and shown the hole in the floor and hired a company to fix it. While the repaired section of the floor appears solid; the surrounding floor still appears to be hollow and unsafe. Currently we have an emb-190 aircraft sitting over that section of concrete floor; up on jacks; with the main landing gear removed. Every time a mechanic working in the wheel wells or under the wings drops a tool on the floor; it makes a very unsettling; hollow noise. If this section of floor would give out and the plane slips off the jacks; there is no question that many mechanics or inspectors would be killed or hurt. This is an old hangar; not originally designed to handle the weight of these aircraft; manlifts; toolboxes and stands that we have sitting on them. I believe we should no longer ignore this issue and ask for any assistance that you can provide to have this floor examined by true professionals or engineers.I'm not exactly sure why this issue has gone on as long as it has; other than assuming someone else has brought up; or that the floor was properly fixed the first time; or scared to say anything to management.

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Original NASA ASRS Text

Title: A Mechanic reports about an unsafe working environment at their company Maintenance Base hangar where the floor under the Heavy C-Check line for their EMB-170/190 aircraft is hollow and appears unstable; raising concerns about serious injuries. An aircraft jack had previously collapsed through the floor when jacking an EMB-170 aircraft.

Narrative: I am submitting this report to report an unsafe working environment at the ZZZ Maintenance hangar. The hangar floor; particularly under the Heavy C-check area; is hollow and appears to be unstable. As I have learned since working here over the years; when this hangar was originally built in the 1940's the offices; bathrooms; hallways and such were all underground. This situation apparently worked fine for them; but they were building much smaller aircraft; in a factory setting. As of now; it appears that the basement has been backfilled and access to the basement obviously sealed off. In 2010; when a Mechanic was using a floor jack to jack up an EMB-170 Left-Hand (L/H) Main Landing Gear (MLG); once the gear was lifted up the floor jack went right through the floor. I was present at that time and reached in the hole to get the jack that was lying on gravel about a foot underneath the floor. Inside the hole I could see a large open void which appeared to be a bathroom underneath the floor.Management was informed of the incident and shown the hole in the floor and hired a company to fix it. While the repaired section of the floor appears solid; the surrounding floor still appears to be hollow and unsafe. Currently we have an EMB-190 aircraft sitting over that section of concrete floor; up on jacks; with the Main Landing Gear removed. Every time a Mechanic working in the wheel wells or under the wings drops a tool on the floor; it makes a very unsettling; hollow noise. If this section of floor would give out and the plane slips off the jacks; there is no question that many mechanics or inspectors would be killed or hurt. This is an old hangar; not originally designed to handle the weight of these aircraft; manlifts; toolboxes and stands that we have sitting on them. I believe we should no longer ignore this issue and ask for any assistance that you can provide to have this floor examined by true professionals or engineers.I'm not exactly sure why this issue has gone on as long as it has; other than assuming someone else has brought up; or that the floor was properly fixed the first time; or scared to say anything to Management.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.