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Here McDonnell Douglas does not use the roller-type seal. Their own method uses doors that pivot out of the stabilizer's way. From their patent:

Click either for larger size

In your photo you can see the hinge line of the upper door (42) as well. Their method inherently doesn't fully cover the opening at large deflections, which is "permissible":

While it is important that the cutout portion be covered by fairings or doors during the cruise attitude of the stabilizer, it is less important in the extreme positions of takeoff, climb or landing, all of which occur at lesser airspeeds. Thus, while one of the doors is pivoted inwardly on one stabilizer surface to permit stabilizer movement in that direction, the extreme pivotal movement of the stabilizer may cause a gap or air space between the other door and movable fairing on the other stabilizer surface. However, this is permissible since it occurs only when the aircraft is in a non-cruise attitude.

— Backlund, J., and R. Gibbs. "Fuselage seal." U.S. Patent No. 3,756,529. 4 Sep. 1973. Current Assignee: McDonnell Douglas Corp

You can also see it on the DC-10-derived MD-11:

— Rob Schleiffert via flickr.com [cropped]

Tip: search for photos of landing to get more hits, as this is when the THS is at a high trailing edge up position (taxiing for takeoff may also work).

Here McDonnell Douglas does not use the roller-type seal. Their own method uses doors that pivot out of the stabilizer's way. From their patent:

In your photo you can see the hinge line of the upper door (42) as well. Their method inherently doesn't fully cover the opening at large deflections, which is "permissible":

While it is important that the cutout portion be covered by fairings or doors during the cruise attitude of the stabilizer, it is less important in the extreme positions of takeoff, climb or landing, all of which occur at lesser airspeeds. Thus, while one of the doors is pivoted inwardly on one stabilizer surface to permit stabilizer movement in that direction, the extreme pivotal movement of the stabilizer may cause a gap or air space between the other door and movable fairing on the other stabilizer surface. However, this is permissible since it occurs only when the aircraft is in a non-cruise attitude.

— Backlund, J., and R. Gibbs. "Fuselage seal." U.S. Patent No. 3,756,529. 4 Sep. 1973. Current Assignee: McDonnell Douglas Corp

You can also see it on the DC-10-derived MD-11:

— Rob Schleiffert via flickr.com [cropped]

Tip: search for photos of landing to get more hits, as this is when the THS is at a high trailing edge up position (taxiing for takeoff may also work).

That's the way McDonnell Douglas rolls. The opening is sealed by doors, but not fully. From their patent:

Click either for larger size

At larger deflection angles as your photo shows, the upper "triangularly shaped door (42)" does not fully close the gap (you can see its hinge line too), which is "permissible":

While it is important that the cutout portion be covered by fairings or doors during the cruise attitude of the stabilizer, it is less important in the extreme positions of takeoff, climb or landing, all of which occur at lesser airspeeds. Thus, while one of the doors is pivoted inwardly on one stabilizer surface to permit stabilizer movement in that direction, the extreme pivotal movement of the stabilizer may cause a gap or air space between the other door and movable fairing on the other stabilizer surface. However, this is permissible since it occurs only when the aircraft is in a non-cruise attitude.

— Backlund, J., and R. Gibbs. "Fuselage seal." U.S. Patent No. 3,756,529. 4 Sep. 1973. Current Assignee: McDonnell Douglas Corp

You can also see it on the DC-10-derived MD-11:

— Rob Schleiffert via flickr.com [cropped]

Tip: search for photos of landing to get more hits, as this is when the THS is at a high trailing edge up position (taxiing for takeoff may also work).

Here McDonnell Douglas does not use the roller-type seal. Their own method uses doors that pivot out of the stabilizer's way. From their patent:

Click either for larger size

In your photo you can see the hinge line of the upper door (42) as well. Their method inherently doesn't fully cover the opening at large deflections, which is "permissible":

While it is important that the cutout portion be covered by fairings or doors during the cruise attitude of the stabilizer, it is less important in the extreme positions of takeoff, climb or landing, all of which occur at lesser airspeeds. Thus, while one of the doors is pivoted inwardly on one stabilizer surface to permit stabilizer movement in that direction, the extreme pivotal movement of the stabilizer may cause a gap or air space between the other door and movable fairing on the other stabilizer surface. However, this is permissible since it occurs only when the aircraft is in a non-cruise attitude.

— Backlund, J., and R. Gibbs. "Fuselage seal." U.S. Patent No. 3,756,529. 4 Sep. 1973. Current Assignee: McDonnell Douglas Corp

You can also see it on the DC-10-derived MD-11:

— Rob Schleiffert via flickr.com [cropped]

Tip: search for photos of landing to get more hits, as this is when the THS is at a high trailing edge up position (taxiing for takeoff may also work).

That's the way McDonnell Douglas rolls. The opening is sealed by doors, but not fully. From their patent:

Click either for larger size

At larger deflection angles as your photo shows, the upper "triangularly shaped door (42)" does not fully close the gap (you can see its hinge line too), which is "permissible":

While it is important that the cutout portion be covered by fairings or doors during the cruise attitude of the stabilizer, it is less important in the extreme positions of takeoff, climb or landing, all of which occur at lesser airspeeds. Thus, while one of the doors is pivoted inwardly on one stabilizer surface to permit stabilizer movement in that direction, the extreme pivotal movement of the stabilizer may cause a gap or air space between the other door and movable fairing on the other stabilizer surface. However, this is permissible since it occurs only when the aircraft is in a non-cruise attitude.

— Backlund, J., and R. Gibbs. "Fuselage seal." U.S. Patent No. 3,756,529. 4 Sep. 1973. Current Assignee: McDonnell Douglas Corp

That's the way McDonnell Douglas rolls. The opening is sealed by doors, but not fully. From their patent:

Click either for larger size

At larger deflection angles as your photo shows, the upper "triangularly shaped door (42)" does not fully close the gap (you can see its hinge line too), which is "permissible":

While it is important that the cutout portion be covered by fairings or doors during the cruise attitude of the stabilizer, it is less important in the extreme positions of takeoff, climb or landing, all of which occur at lesser airspeeds. Thus, while one of the doors is pivoted inwardly on one stabilizer surface to permit stabilizer movement in that direction, the extreme pivotal movement of the stabilizer may cause a gap or air space between the other door and movable fairing on the other stabilizer surface. However, this is permissible since it occurs only when the aircraft is in a non-cruise attitude.

— Backlund, J., and R. Gibbs. "Fuselage seal." U.S. Patent No. 3,756,529. 4 Sep. 1973. Current Assignee: McDonnell Douglas Corp

You can also see it on the DC-10-derived MD-11:

— Rob Schleiffert via flickr.com [cropped]

Tip: search for photos of landing to get more hits, as this is when the THS is at a high trailing edge up position (taxiing for takeoff may also work).